Higgs boson

{{Short description|Elementary particle involved with rest mass}} {{Redirect|God Particle|other uses|The God Particle (disambiguation)}} {{pp-move|small=yes}} {{pp-pc}} {{Use British English|date=May 2020}} {{Use dmy dates|date=February 2024}} {{Infobox particle | name = Higgs boson | image = Candidate Higgs Events in ATLAS and CMS.png | caption = Candidate Higgs boson events from [[particle collision|collisions]] between [[proton]]s in the [[LHC]]. The top event in the [[Compact Muon Solenoid|CMS]] experiment shows a decay into two [[photon]]s (dashed yellow lines and green towers). The lower event in the [[ATLAS experiment|ATLAS]] experiment shows a decay into four [[muon]]s (red tracks).{{efn|Note that such events also occur due to other processes. Detection involves a [[statistically significant]] excess of such events at specific energies.}} | composition = [[Elementary particle]] | statistics = [[Bose–Einstein statistics]] | family = [[Scalar boson]] | interaction = [[Gravity]], [[electroweak]] | particle = | antiparticle = Self | theorised = [[Robert Brout|R. Brout]], [[François Englert|F. Englert]], [[Peter Higgs|P. Higgs]], [[Gerald Guralnik|G. S. Guralnik]], [[C. R. Hagen]], and [[T. W. B. Kibble]] (1964) | discovered = [[Large Hadron Collider]] (2011–2013) | symbol = {{SubatomicParticle|Higgs boson}} | mass = {{val|125.11|0.11}} {{val|ul=GeV/c2}}<ref>{{cite web |url=https://home.cern/news/news/physics/atlas-sets-record-precision-higgs-bosons-mass |title=ATLAS sets record precision on Higgs boson's mass |date=21 July 2023 |access-date=22 July 2023 |url-status=live |archive-date=22 July 2023 |archive-url=https://web.archive.org/web/20230722110945/https://home.cern/news/news/physics/atlas-sets-record-precision-higgs-bosons-mass }}</ref> | mean_lifetime = {{val|1.56|e=-22|u=s}}{{efn|name=meanlife| In the [[Standard Model]], the total [[decay width]] of a Higgs boson with a mass of {{val|125|u=GeV/c2}} is predicted to be {{val|4.07|e=-3|u=GeV}}.<ref name="LHCcrosssections"> {{cite report |collaboration=LHC Higgs Cross Section Working Group |last1=Dittmaier |last2=Mariotti |last3=Passarino |last4=Tanaka |last5=Alekhin |last6=Alwall |last7=Bagnaschi |last8=Banfi |year=2012 |title=Handbook of LHC Higgs Cross Sections: 2. Differential Distributions |series=CERN Report 2 (Tables A.1–A.20) |volume=1201 |page=3084 |arxiv=1201.3084 |bibcode = 2012arXiv1201.3084L |doi=10.5170/CERN-2012-002 |s2cid=119287417 }}</ref> The mean lifetime is given by {{tmath|1= \tau = \hbar/\Gamma }}. }} (predicted){{pb}}{{nowrap|1.2 ~ {{val|4.6|e=-22|u=s}}}} (tentatively measured at 3.2 sigma (1 in 1000) significance)<ref name="lifetime1">{{cite press release |url=https://cms.cern/news/life-higgs-boson |title=Life of the Higgs boson |publisher=CMS Collaboration |access-date=21 January 2021 |url-status=live |archive-date=2 December 2021 |archive-url=https://web.archive.org/web/20211202001531/https://cms.cern/news/life-higgs-boson }}</ref><ref name="lifetime2-dalitz">{{cite press release |url=https://home.cern/news/news/physics/atlas-finds-evidence-rare-higgs-boson-decay |title=ATLAS finds evidence of a rare Higgs boson decay |publisher=CERN |date=8 February 2021 |access-date=21 January 2022 |url-status=live |archive-date=19 January 2022 |archive-url=https://web.archive.org/web/20220119031015/https://home.cern/news/news/physics/atlas-finds-evidence-rare-higgs-boson-decay }}</ref> | decay_particle = {{ubl | [[Bottom quark|Bottom]]–antibottom pair (observed)<ref>{{cite journal |arxiv=1808.08238 |title=Observation of H→b{{overline|b}} decays and VH production with the ATLAS detector |journal=Physics Letters B |volume=786 |pages=59–86 |author=[[ATLAS collaboration]] |year=2018 |doi=10.1016/j.physletb.2018.09.013 |s2cid=53658301}}</ref><ref>{{cite journal |arxiv=1808.08242 |doi=10.1103/PhysRevLett.121.121801 |pmid=30296133 |title=Observation of Higgs boson decay to bottom quarks |journal=Physical Review Letters |volume=121 |issue=12 |article-number=121801 |year=2018 |author=CMS collaboration |bibcode=2018PhRvL.121l1801S |s2cid=118901756}}</ref> | Two [[W boson]]s (observed) | Two [[gluon]]s (predicted) | [[Tau lepton|Tau]]–antitau pair (observed) | Two [[Z boson]]s (observed) | Two [[photon]]s (observed) | Two [[lepton]]s and a [[photon]] (Dalitz decay via [[virtual photon]]) (tentatively observed at sigma 3.2 (1 in 1,000) significance)<ref name="lifetime2-dalitz"/> | [[Muon]]–antimuon pair (predicted) | Various other decays (predicted) }} | electric_charge = 0 ''e'' | spin = 0 [[reduced Planck constant|''ħ'']]{{px2}}<ref name="CERN March 2013" /><ref name="CMSspinparity2017">{{cite journal |arxiv=1707.00541 |author=CMS Collaboration |title=Constraints on anomalous Higgs boson couplings using production and decay information in the four-lepton final state |journal=Physics Letters B |volume=775 |issue=2017 |pages=1–24 |year=2017 |doi=10.1016/j.physletb.2017.10.021 |bibcode=2017PhLB..775....1S |s2cid=3221363}}</ref> | parity = +1<ref name="CERN March 2013"/><ref name=CMSspinparity2017/> | num_spin_states = | c_parity = +1 | color_charge = No }}

The '''Higgs boson''', sometimes called the '''Higgs particle''',<ref>{{cite web |url=https://atlas.cern/updates/blog/what-should-we-know-about-higgs-particle |title=What should we know about the Higgs particle? |last=Goulette |first=Marc |publisher=Atlas Experiment / [[CERN]] |date=15 August 2012 |type=blog |access-date=21 January 2022 |url-status=live |archive-date=13 January 2022 |archive-url=https://web.archive.org/web/20220113145217/https://atlas.cern/updates/blog/what-should-we-know-about-higgs-particle }}</ref><ref>{{cite press release |url=https://www.iop.org/education/school-and-college-students/Qubit/higgs-particle-new-discoveries |title=Getting to know the Higgs particle: New discoveries! |publisher=Institute of Physics |access-date=21 January 2022 |url-status=live |archive-date=13 January 2022 |archive-url=https://web.archive.org/web/20220113155023/https://www.iop.org/education/school-and-college-students/Qubit/higgs-particle-new-discoveries }}</ref> is an [[elementary particle]] in the [[Standard Model]] of [[particle physics]] produced by the [[excited state|quantum excitation]] of the [[Higgs field]],<ref name=OnyisiFAQ> {{cite web |last=Onyisi |first=P. |date=23 October 2012 |title=Higgs boson FAQ |publisher=[[University of Texas]] ATLAS group |url=https://wikis.utexas.edu/display/utatlas/Higgs+boson+FAQ |access-date=8 January 2013 |url-status=live |archive-url=https://web.archive.org/web/20131012130340/https://wikis.utexas.edu/display/utatlas/Higgs+boson+FAQ |archive-date=12 October 2013 }} </ref><ref name=strasslerFAQ2> {{cite web |last=Strassler |first=M. |date=12 October 2012 |title=The Higgs FAQ 2.0 |website=ProfMattStrassler.com |url=http://profmattstrassler.com/articles-and-posts/the-higgs-particle/the-higgs-faq-2-0/ |access-date=8 January 2013 |url-status=live |archive-url=https://web.archive.org/web/20131012042637/http://profmattstrassler.com/articles-and-posts/the-higgs-particle/the-higgs-faq-2-0/ |archive-date=12 October 2013 |quote=[Q] Why do particle physicists care so much about the Higgs particle?{{pb}}[A] Well, actually, they don't. What they really care about is the Higgs {{em|field}}, because it is {{em|so}} important. [emphasis in original] }}</ref> one of the [[field (physics)|fields]] in [[particle physics]] theory.<ref name=strasslerFAQ2/> In the Standard Model, the Higgs particle is a massive [[scalar boson]] that [[Coupling (physics)|couples]] to (interacts with) particles whose mass arises from their interactions with the Higgs field, has zero [[Spin (physics)|spin]], even (positive) [[Parity (physics)|parity]], no [[electric charge]], and no [[color charge|color charge]].<ref name="when higgs"/> It is also very unstable, [[particle decay|decaying]] into other particles almost immediately upon generation.

The Higgs field is a [[scalar field]] with two neutral and two electrically charged components that form a complex [[doublet (physics)|doublet]] of the [[weak isospin]] SU(2) symmetry. Its "[[Spontaneous symmetry breaking#Sombrero potential|sombrero potential]]" leads it to take a nonzero value everywhere (including otherwise empty space), which [[spontaneous symmetry breaking|breaks]] the [[weak isospin]] symmetry of the [[electroweak interaction]] and, via the [[Higgs mechanism]], gives a rest mass to all massive elementary particles of the Standard Model, including the Higgs boson itself. The existence of the Higgs field became the last unverified part of the Standard Model of particle physics, and for several decades was considered "the central problem in particle physics".<ref name=Proceedings_1986/><ref name=Higgs_Hunters_Guide/>

Both the field and the [[boson]] are named after physicist [[Peter Higgs]], who in 1964, [[1964 PRL symmetry breaking papers|along with five other scientists]] in three teams, proposed the [[Higgs mechanism]], a way for [[mass generation|some particles to acquire mass]]. All fundamental particles known at the time{{efn|In Higgs-based theories, the Higgs boson itself should be an exception, being massive even at high energies.}} should be massless at very high energies, but fully explaining how some particles gain mass at lower energies had been extremely difficult. If these ideas were correct, a particle known as a scalar boson (with certain properties) should also exist. This particle was called the Higgs boson and could be used to test whether the Higgs field was the correct explanation.

After a [[Search for the Higgs boson|40-year search]], a subatomic particle with the expected properties was discovered in 2012 by the [[ATLAS experiment|ATLAS]] and [[Compact Muon Solenoid|CMS]] experiments at the [[Large Hadron Collider]] (LHC) at [[CERN]] near [[Geneva]], Switzerland. The new particle was subsequently confirmed to match the expected properties of a Higgs boson. Physicists from two of the three teams, [[Peter Higgs]] and [[François Englert]], were awarded the [[Nobel Prize in Physics]] in 2013 for their theoretical predictions. Although Higgs's name has come to be associated with this theory, several researchers between about 1960 and 1972 independently developed different parts of it.

In the media, the Higgs boson has often been called the "'''God particle'''" after the 1993 book ''[[The God Particle (book)|The God Particle]]'' by Nobel Laureate [[Leon M. Lederman]]. The name has been criticised by physicists,<ref name=ISample29052009> {{cite news |last=Sample |first=Ian |date=29 May 2009 |title=Anything but the God particle |newspaper=[[The Guardian]] |url=https://www.theguardian.com/science/blog/2009/may/29/why-call-it-the-god-particle-higgs-boson-cern-lhc |access-date=24 June 2009 |url-status=live |archive-url=https://web.archive.org/web/20180725112437/https://www.theguardian.com/science/blog/2009/may/29/why-call-it-the-god-particle-higgs-boson-cern-lhc |archive-date=25 July 2018 }} </ref><ref name="NatPost"> {{cite news |last=Evans |first=Robert |date=14 December 2011 |title=The Higgs boson: Why scientists hate that you call it the 'God particle' |url=https://nationalpost.com/news/the-higgs-boson-why-scientists-hate-that-you-call-it-the-god-particle |url-status=live |archive-url=https://web.archive.org/web/20150223003531/http://news.nationalpost.com/2011/12/14/the-higgs-boson-why-scientists-hate-that-you-call-it-the-god-particle/ |archive-date=23 February 2015 |access-date=3 November 2013 |newspaper=[[National Post]]}} </ref> including Peter Higgs.<ref>{{ cite web | url=https://www.reuters.com/article/idUSL07652872/ | title=Key scientist sure "God particle" will be found soon | first=Robert | last=Evans | editor1-first=Jonathan | editor1-last=Lynn | editor2-first=Chloe | editor2-last=Fussell | website=[[Reuters]] | location=[[Geneva]] | date=7 April 2008 | access-date=4 June 2024 }}</ref>

== Introduction == {{Standard model of particle physics|Introduction to gauge theory}}

=== Standard Model === Physicists explain the [[fundamental particle]]s and [[fundamental interaction|forces]] of the universe in terms of the [[Standard Model]] – a widely accepted framework based on [[quantum field theory]] that predicts almost all known particles and forces aside from [[gravity]] with great accuracy. (A separate theory, [[general relativity]], is used for gravity.) In the Standard Model, the particles and forces in nature (aside from gravity) arise from properties of [[quantum field]]s known as [[Introduction to gauge theory|gauge invariance]] and [[Symmetry (physics)|symmetries]]. Forces in the Standard Model are [[force carrier|transmitted by particles]] known as [[gauge boson]]s.<ref>{{harvnb|Griffiths|2008|pp=49–52}}</ref><ref>{{harvnb|Tipler|Llewellyn|2003|pp=603–604}}</ref>

=== Gauge-invariant theories and symmetries === : ''"It is only slightly overstating the case to say that physics is the study of symmetry"'' – [[Philip W. Anderson|Philip Anderson]], Nobel Prize Physics<ref>From P.W. Anderson (1972) "More is different", Science.</ref>

[[Introduction to gauge theory|Gauge-invariant theories]] are theories with a useful feature, namely that changes to certain quantities make no difference to experimental outcomes. For example, increasing the [[electric potential]] of an [[electromagnet]] by 100 volts does not itself cause any change to the [[magnetic field]] that it produces. Similarly, the measured [[speed of light]] in vacuum remains unchanged, whatever the location in time and space, and whatever the local [[gravitational field]].

In these theories, the gauge is a quantity that can be changed with no resultant effect. This independence of the results from some changes is called gauge invariance, and these changes reflect symmetries of the underlying physics. These symmetries provide constraints on the fundamental forces and particles of the physical world. Gauge invariance is therefore an important property within particle physics theory. The gauge symmetries are closely connected to [[conservation law]]s and are described mathematically using [[group theory]]. Quantum field theory and the Standard Model are both gauge-invariant theories – meaning that the gauge symmetries allow theoretical derivation of properties of the universe.

=== Gauge boson rest mass problem === Quantum field theories based on gauge invariance had been used with great success in understanding the [[Electromagnetic force|electromagnetic]] and [[strong force]]s, but by around 1960, all attempts to create a ''gauge invariant'' theory for the [[weak force]] (and its combination with the electromagnetic force, known together as the [[electroweak interaction]]) had consistently failed. As a result of these failures, gauge theories began to fall into disrepute. The problem was that [[Symmetry (physics)|symmetry requirements]] for these two forces incorrectly predicted that the weak force's gauge bosons ([[W and Z bosons|W and Z]]) would have zero mass (in the specialized terminology of particle physics, "mass" refers specifically to a particle's [[rest mass]]). But experiments showed the W and Z gauge bosons had non-zero (rest) mass.<ref>{{harvnb|Griffiths|2008|pp=372–373}}</ref>

Further, many promising solutions seemed to require the existence of extra particles known as [[Goldstone boson]]s, but evidence suggested these did not exist. This meant that either gauge invariance was an incorrect approach, or something unknown was giving the weak force's W and Z bosons their mass, and doing it in a way that did not imply the existence of Goldstone bosons. By the late 1950s and early 1960s, physicists were at a loss as to how to resolve these issues, or how to create a comprehensive theory for particle physics.

=== Symmetry breaking === In the late 1950s, [[Yoichiro Nambu]] recognised that [[spontaneous symmetry breaking]], a process whereby a symmetric system becomes asymmetric, could occur under certain conditions.{{efn| In physics, it is possible for a [[scientific law|law]] to hold true only if certain assumptions hold true, or when certain conditions are met. For example, [[Newton's laws of motion]] only apply at speeds where [[Special relativity|relativistic effects]] are negligible; and laws related to conductivity, gases, and classical physics (as opposed to quantum mechanics) may apply only within certain ranges of size, temperature, pressure, or other conditions. }} Symmetry breaking is when some variable takes on a value that does not reflect the symmetries that the underlying laws have, such as when the space of all stable configurations possesses a given symmetry but the stable configurations do not individually possess that symmetry.{{efn|An example to illustrate this is where a pencil is balancing on its tip, any disturbance will lead it to fall over in some direction. The underlying system is symmetric with respect to direction, but the pencil will fall in some direction, leading to a broken directional symmetry.}} In 1962, physicist [[Philip Warren Anderson|Philip Anderson]], an expert in [[condensed matter physics]], observed that symmetry breaking plays a role in [[superconductivity]], and suggested that it could also be part of the answer to the problem of gauge invariance in particle physics.

Specifically, Anderson suggested that the [[Goldstone boson]]s that would result from symmetry breaking might instead, in some circumstances, be "absorbed"{{efn| In theoretical particle physics, one says that particle {{sc|A}} "absorbs" particle {{sc|B}} when they always act simultaneously, and their combined effect cannot be separated using observables: Although the mathematical description of the process may have two parts, {{sc|A}} and {{sc|B}}, the observed preconditions and their outcomes are indistinguishable from the interaction of what appears to effectively be a single particle (which usually is given another, slightly different name; for example one of the combinations of the theoretical {{math|W{{sub|3}}}} and {{math|B{{sup|0}}}} [[electroweak]] bosons is called the [[Z boson]]). }} by the massless [[W and Z bosons]]. If so, perhaps the Goldstone bosons would not exist, and the W and Z bosons could [[mass generation|gain mass]], solving both problems at once. Similar behaviour was already theorised in superconductivity.<ref name=woit/> In 1964, this was shown to be theoretically possible by physicists [[Abraham Klein (physicist)|Abraham Klein]] and [[Benjamin W. Lee|Benjamin Lee]], at least for some limited ([[special relativity|non-relativistic]]) cases.<ref name=Klein-Lee-1964/>

=== Higgs mechanism === {{Main|Higgs mechanism|Standard Model}} Following the 1963<ref name=Anderson-1963/> and early 1964<ref name=Klein-Lee-1964/> papers, three groups of researchers independently developed these theories more completely, in what became known as the [[1964 PRL symmetry breaking papers]]. All three groups reached similar conclusions and for all cases, not just some limited cases. They showed that the conditions for electroweak symmetry would be "broken" if an unusual type of [[field (physics)|field]] existed throughout the universe, and indeed, there would be no Goldstone bosons and some existing bosons would [[mass generation|acquire mass]].

The field required for this to happen (which was purely hypothetical at the time) became known as the ''Higgs field'' (after [[Peter Higgs]], one of the researchers) and the mechanism by which it led to symmetry breaking became known as the ''[[Higgs mechanism]]''. A key feature of the necessary field is that the field would have ''less'' energy when it had a non-zero value than when it was zero, unlike every other known field; therefore, the Higgs field has a non-zero value (or ''[[Vacuum expectation value|vacuum expectation]]'') everywhere. This non-zero value could in theory break electroweak symmetry. It was the first proposal that was able to show, within a gauge invariant theory, how the weak force gauge bosons could have mass despite their governing symmetry.

Although these ideas did not gain much initial support or attention, by 1972 they had been developed into a comprehensive theory and gave [[renormalization|"sensible" results]] that accurately described particles known at the time, and which, with exceptional accuracy, [[Standard Model#Tests and predictions|predicted several other particles, which were discovered during the following years]].{{efn|name="predictions"| The success of the Higgs-based electroweak theory and Standard Model is illustrated by their [[Standard Model#Tests and predictions|predictions]] of the mass of two particles that were later detected: the W boson (predicted mass: {{val|80.390|0.018|u=GeV/c2}}, experimental measurement: {{val|80.387|0.019|u=GeV/c2}}), and the Z boson (predicted mass: {{val|91.1874|0.0021|u=GeV/c2}}, experimental measurement: {{val|91.1876|0.0021|u=GeV/c2}}). Other accurate predictions included the [[weak neutral current]], the [[gluon]], and the [[top quark|top]] and [[charm quark]]s, all later proven to exist. }} During the 1970s, these theories rapidly became the [[Standard Model]] of particle physics.

=== Higgs field === To allow symmetry breaking, the Standard Model includes a [[field (physics)|field]] of the kind needed to "break" electroweak symmetry and give particles their correct mass. This field, which became known as the Higgs field, was hypothesized to exist throughout space, and to break some symmetry laws of the [[electroweak interaction]], triggering the Higgs mechanism. It would therefore cause the W and Z gauge bosons of the weak force to be massive at all temperatures below an extremely high value.{{efn|Electroweak symmetry is broken by the Higgs field in its lowest energy state, called its ''[[ground state]]''. At high energy levels this does not happen, and the gauge bosons of the weak force would be expected to become massless above those energy levels.}} When the weak force bosons acquire mass, this affects the distance they can freely travel, which becomes very small, also matching experimental findings.{{efn| name=massvsrange| The range of a force is inversely proportional to the mass of the particles transmitting it.<ref> {{cite book |last=Shu |first=F. H. |year=1982 |title=The Physical Universe: An introduction to astronomy |pages=107–108 |publisher=University Science Books |isbn=978-0-935702-05-7 |url=https://books.google.com/books?id=v_6PbAfapSAC&pg=PA107 |access-date=27 June 2015 |url-status=live |archive-url=https://web.archive.org/web/20160629141232/https://books.google.com/books?id=v_6PbAfapSAC&pg=PA107 |archive-date=29 June 2016 }} </ref> : In the Standard Model, forces are carried by [[virtual particles]]. The movement and interactions of these particles with each other are limited by the energy–time [[uncertainty principle]]. As a result, the more massive a single virtual particle is, the greater its energy, and therefore the shorter the distance it can travel. A particle's mass therefore, determines the maximum distance at which it can interact with other particles and on any force it mediates. By the same token, the reverse is also true: Massless and near-massless particles can carry long distance forces. : Since experiments have shown that the weak force acts over only a very short range, this implies that massive gauge bosons must exist, and indeed, their masses have since been confirmed by measurement. : ''(See also: [[Compton wavelength]] and [[static forces and virtual-particle exchange]])'' }} Furthermore, it was later realised that the same field would also explain, in a different way, why other fundamental constituents of matter (including [[electron]]s and [[quark]]s) have mass.

Unlike all other known fields, such as the [[electromagnetic field]], the Higgs field is a [[scalar field]], and has a non-zero average value in [[Vacuum state|vacuum]].

=== The "central problem" === Prior to the discovery of the Higgs Boson, there was no direct evidence that the Higgs field exists, but even without direct evidence, the accuracy of predictions within the Standard Model led scientists to believe the theory might be correct. By the 1980s, the question of whether the Higgs field exists, and whether the entire Standard Model is correct, had come to be regarded as one of the most important [[Unanswered questions in physics|unanswered questions in particle physics]]. The existence of the Higgs field became the last unverified part of the Standard Model of particle physics, and for several decades was considered "the central problem in particle physics".<ref name=Proceedings_1986/><ref name=Higgs_Hunters_Guide/>

For many decades, scientists had no way to determine whether the Higgs field exists because the technology needed for its detection did not exist at that time. If the Higgs field did exist, then it would be unlike any other known fundamental field, but it also was possible that these key ideas, or even the entire Standard Model, were somehow incorrect.{{efn|By the 1960s, many had already started to see gauge theories as failing to explain particle physics, because theorists had been unable to solve the mass problem or even explain how gauge theory could provide a solution. So the idea that the Standard Model – which relied on a Higgs field, not yet proved to exist – could be fundamentally incorrect was not unreasonable. : Against this, once the model was developed around 1972, no better theory existed, and its predictions and solutions were so accurate that it became the preferred theory anyway. It then became crucial to science to know whether it was correct. }}

The hypothesised Higgs theory made several key predictions.{{efn|name=predictions}}<ref name="L&T"/>{{rp|22}} One crucial prediction was that a matching [[subatomic particle|particle]], called the Higgs boson, should also exist. Proving the existence of the Higgs boson would prove the existence of the Higgs field, and therefore finally prove the Standard Model. Therefore, there was an extensive [[search for the Higgs boson]] as a way to prove the Higgs field itself exists.<ref name=OnyisiFAQ/><ref name=strasslerFAQ2/>

=== Search and discovery === Although the Higgs field would exist and be nonzero everywhere, proving its existence was far from easy. In principle, it can be proved to exist by detecting its [[excited state|excitations]], which manifest as Higgs particles (Higgs bosons), but these are extremely difficult to produce and detect due to the energy required to produce them and their very rare production even if there is sufficient energy available. It was, therefore, several decades before the first evidence of the Higgs boson would be found. [[Particle collider]]s, detectors, and computers capable of looking for Higgs bosons took more than 30 years {{nowrap|({{circa|1980–2010}})}} to develop. The importance of this [[Unanswered questions in physics|fundamental question]] led to a [[Search for the Higgs boson|40-year search]], and the construction of one of the world's most [[List of megaprojects#Science projects|expensive and complex experimental facility]] to date, [[CERN]]'s [[Large Hadron Collider]] (LHC),<ref name="Strassler article">{{cite web |last=Strassler |first=M. |date=8 October 2011 |title=The known particles – if the Higgs field were zero |website=ProfMattStrassler.com |url=http://profmattstrassler.com/articles-and-posts/particle-physics-basics/the-known-apparently-elementary-particles/the-known-particles-if-the-higgs-field-were-zero/ |access-date=13 November 2012 |url-status=live |archive-url=https://web.archive.org/web/20210317211303/https://profmattstrassler.com/articles-and-posts/particle-physics-basics/the-known-apparently-elementary-particles/the-known-particles-if-the-higgs-field-were-zero/ |archive-date=17 March 2021 |quote=The Higgs field: So important it merited an entire experimental facility, the Large Hadron Collider, dedicated to understanding it.}}</ref> in an attempt to create Higgs bosons and other particles for observation and study.

On 4 July 2012, the discovery of a new particle with a mass between {{val|125|and|127|ul=GeV/c2}} was announced; physicists suspected that it was the Higgs boson.<ref name=Biever-2012-07-Dieter>{{cite news |last=Biever |first=C. |date=6 July 2012 |title=It's a boson! But we need to know if it's the Higgs |magazine=[[New Scientist]] |url=https://www.newscientist.com/article/dn22029-its-a-boson-but-we-need-to-know-if-its-the-higgs.html |access-date=9 January 2013}}</ref>{{efn|''Discovery press conference'', July 2012: : 'As a layman, I would say, I think we have it', said Rolf-Dieter Heuer, director general of CERN at Wednesday's seminar announcing the results of the search for the Higgs boson. But when pressed by journalists afterwards on what exactly 'it' was, things got more complicated. : 'We have discovered a boson; now we have to find out what boson it is' [Q]: 'If we don't know the new particle is a Higgs, what do we know about it?' [A]: We know it is some kind of boson, says Vivek Sharma of CMS [...] [Q]: 'are the CERN scientists just being too cautious? What would be enough evidence to call it a Higgs boson?' [A]: As there could be many different kinds of Higgs bosons, there's no straight answer.<ref name=Biever-2012-07-Dieter/> :: [''emphasis in original'']}}<ref name=ScienceNews>{{cite news |last=Siegfried |first=T. |date=20 July 2012 |title=Higgs hysteria |website=[[Science News]] |url=http://www.sciencenews.org/view/generic/id/342408/title/Blog_Higgs_hysteria |access-date=9 December 2012 |url-status=live |archive-date=31 October 2012 |archive-url=https://web.archive.org/web/20121031090612/http://www.sciencenews.org/view/generic/id/342408/title/Blog_Higgs_hysteria |quote=In terms usually reserved for athletic achievements, news reports described the finding as a monumental milestone in the history of science.}}</ref><ref name="CERN Nov 2012">{{cite press release |last=Del Rosso |first=A. |date=19 November 2012 |title=Higgs: The beginning of the exploration |publisher=[[CERN]] |issue=47–48 |url=https://cds.cern.ch/record/1494477?ln=en |access-date=9 January 2013 |url-status=live |archive-url=https://web.archive.org/web/20190419214711/https://cds.cern.ch/record/1494477?ln=en |archive-date=19 April 2019 |quote=Even in the most specialized circles, the new particle discovered in July is not yet being called the "Higgs boson". Physicists still hesitate to call it that before they have determined that its properties fit with those the Higgs theory predicts the Higgs boson has.}}</ref> Since then, the particle has been shown to behave, interact, and decay in many of the ways predicted for Higgs particles by the Standard Model, including having even [[Parity (physics)|parity]] and zero [[Spin (physics)|spin]],<ref name="CERN March 2013"/><ref name=CMSspinparity2017/> two fundamental attributes of a Higgs boson. This also means it is the first elementary [[scalar boson|scalar particle]] discovered in nature.<ref name="WSJ 14 March 2013">{{cite news |last=Naik |first=G. |date=14 March 2013 |title=New data boosts case for Higgs boson find |newspaper=[[The Wall Street Journal]] |url=https://www.wsj.com/articles/SB10001424127887324077704578359850108689618 |access-date=15 March 2013 |url-status=live |archive-url=https://web.archive.org/web/20180104114526/https://www.wsj.com/articles/SB10001424127887324077704578359850108689618 |archive-date=4 January 2018 |quote='We've never seen an elementary particle with spin zero', said Tony Weidberg, a particle physicist at the University of Oxford who is also involved in the CERN experiments.}}</ref>

By March 2013, the existence of the Higgs boson was confirmed, and therefore the concept of some type of Higgs field throughout space is strongly supported.<ref name=Biever-2012-07-Dieter/><ref name="CERN Nov 2012"/><ref name="CERN March 2013">{{cite press release |last=O'Luanaigh |first=C. |date=14 March 2013 |title=New results indicate that new particle is a Higgs boson |publisher=[[CERN]] |url=http://home.web.cern.ch/about/updates/2013/03/new-results-indicate-new-particle-higgs-boson |access-date=9 October 2013 |url-status=live |archive-url=https://web.archive.org/web/20151020000722/http://home.web.cern.ch/about/updates/2013/03/new-results-indicate-new-particle-higgs-boson |archive-date=20 October 2015 }}</ref> The presence of the field, confirmed by experiment, explains [[mass generation|why some fundamental particles have (a rest) mass]], despite the [[symmetry (physics)|symmetries]] controlling their interactions implying that they should be "massless". It also resolves several other long-standing problems, such as the reason for the extremely short distance travelled by the [[weak interaction|weak force]] bosons, and therefore the weak force's extremely short range. As of 2018, in-depth research shows the particle continuing to behave in line with predictions for the Standard Model's Higgs boson. More studies are needed to verify with higher precision that the discovered particle has all of the properties predicted or whether, as described by some theories, multiple Higgs bosons exist.<ref name="Huffington 14 March 2013">{{cite news |last=Heilprin |first=J. |date=14 March 2013 |title=Higgs boson discovery confirmed after physicists review Large Hadron Collider data at CERN |website=[[The Huffington Post]] |url=https://huffingtonpost.com/2013/03/14/higgs-boson-discovery-confirmed-cern-large-hadron-collider_n_2874975.html?icid=maing-grid7%7Cmain5%7Cdl1%7Csec1_lnk2%26pLid%3D283596 |access-date=14 March 2013 |archive-url=https://web.archive.org/web/20130317191649/http://www.huffingtonpost.com/2013/03/14/higgs-boson-discovery-confirmed-cern-large-hadron-collider_n_2874975.html?icid=maing-grid7%7Cmain5%7Cdl1%7Csec1_lnk2&pLid=283596 |archive-date=17 March 2013}}</ref>

The nature and properties of this field are being investigated further, using more data collected at the LHC.<ref name="CERN_EPS2017">{{cite press release |title=LHC experiments delve deeper into precision |date=11 July 2017 |publisher=[[CERN]] |website=Media and Press relations |url=https://home.cern/news/news/cern/lhc-experiments-delve-deeper-precision |url-status=live |access-date=23 July 2017 |archive-url=https://web.archive.org/web/20181122052040/https://home.cern/news/news/cern/lhc-experiments-delve-deeper-precision |archive-date=22 November 2018}}</ref>

=== Interpretation === [[#Educational explanations and analogies|Various analogies]] have been used to describe the Higgs field and boson, including analogies with well-known symmetry-breaking effects such as the [[rainbow]] and [[dispersive prism|prism]], [[electric field]]s, and ripples on the surface of water.

Other analogies based on the resistance of macroscopic objects moving through media (such as people moving through crowds, or some objects moving through [[syrup]] or [[molasses]]) are commonly used but misleading, since the Higgs field does not actually resist particles, and the effect of mass is not caused by resistance.

=== Overview of Higgs boson and field properties === [[File:Mecanismo de Higgs PH.png|thumb|upright=1|The [[Spontaneous symmetry breaking#Sombrero potential|sombrero potential]] of the Higgs field is responsible for some particles gaining mass.]] In the Standard Model, the '''Higgs''' '''boson''' is a massive [[scalar boson]] whose mass must be found experimentally. Its mass has been determined to be {{val|125.35|0.15|u=GeV/c2}} by CMS (2022)<ref>{{cite web |url=https://cms.cern/news/cms-precisely-measures-mass-higgs-boson |title=CMS precisely measures the mass of the Higgs boson |publisher=CMS Collaboration/CERN |access-date=21 January 2022 |url-status=live |archive-date=23 December 2021 |archive-url=https://web.archive.org/web/20211223042025/https://cms.cern/news/cms-precisely-measures-mass-higgs-boson }}</ref> and {{val|125.11|0.11|u=GeV/c2}} by ATLAS (2023). It is the only particle that remains massive even at very high energies. It has zero [[Spin (physics)|spin]], even (positive) [[Parity (physics)|parity]], no [[electric charge]], no [[color charge|colour charge]], and it [[Coupling (physics)|couples]] to (interacts with) mass.<ref name="when higgs" /> It is also very unstable, [[particle decay|decaying]] into other particles almost immediately via several possible pathways.

The '''Higgs field''' is a [[scalar field]], with two neutral and two electrically charged components that form a complex [[doublet (physics)|doublet]] of the [[weak isospin]] SU(2) symmetry. Unlike any other known quantum field, it has a [[Spontaneous symmetry breaking#Sombrero potential|sombrero potential]]. This shape means that below extremely high cross-over temperature of {{val|159.5|1.5|u=[[Electronvolt#Temperature|GeV/''k''B]]}}<ref>{{cite journal |last1=D'Onofrio |first1=Michela |last2=Rummukainen |first2=Kari |date=15 January 2016 |title=Standard model cross-over on the lattice |journal=[[Physical Review D]] |volume=93 |number=2 |article-number=025003 |arxiv=1508.07161 |doi=10.1103/PhysRevD.93.025003 |bibcode=2016PhRvD..93b5003D |s2cid=119261776 }}</ref> such as [[Chronology of the Universe|those seen]] during the first [[picosecond]] (10−12 s) of the [[Big Bang]], the Higgs field in its [[vacuum state|ground state]] has less energy when it is nonzero, resulting in a nonzero [[vacuum expectation value]]. Therefore, in today's universe the Higgs field has a nonzero value everywhere (including in otherwise empty space). This nonzero value in turn breaks the weak isospin SU(2) symmetry of the [[electroweak interaction]] everywhere. (Technically the non-zero expectation value converts the [[Lagrangian (field theory)|Lagrangian]]'s [[Yukawa coupling]] terms into mass terms.) When this happens, three components of the Higgs field are "absorbed" by the SU(2) and U(1) [[gauge boson]]s (the [[Higgs mechanism]]) to become the longitudinal components of the now-massive [[W and Z bosons]] of the [[weak force]]. The remaining electrically neutral component either manifests as a Higgs boson, or may couple separately to other particles known as [[fermion]]s (via Yukawa couplings), causing these to [[mass generation|acquire mass]] as well.<ref>[https://www.youtube.com/watch?v=JqNg819PiZY Demystifying the Higgs Boson with Leonard Susskind] {{webarchive|url=https://web.archive.org/web/20190401162251/https://www.youtube.com/watch?v=JqNg819PiZY |date=1 April 2019 }}, [[Leonard Susskind]] presents an explanation of what the Higgs mechanism is, and what it means to "give mass to particles". He also explains what's at stake for the future of physics and cosmology. 30 July 2012.</ref>

Even though the knowledge of many of the Higgs boson properties has advanced significantly since its discovery, the Higgs boson's self-coupling remains unmeasured. The shape of the Higgs potential in the [[Standard Model of particle physics|Standard Model]] includes both trilinear and quartic self-couplings, which are key to understanding the complete shape of the potential and the nature of the Higgs field and EWSB. [[Higgs pair production|Higgs boson pair production]] offers a direct experimental probe of the self-coupling λ at the electroweak scale.

== Significance == Evidence for the Higgs field and its properties has been extremely significant for many reasons. The primary importance of the Higgs boson is that it completes the mechanism by which the heavy electroweak bosons acquire mass, and it is fortunate that the mass is such that it is able to be examined using existing experimental technology, as a way to confirm and study the entire Higgs field theory.<ref name="OnyisiFAQ" /><ref name="strasslerFAQ2" /> Conversely, evidence that the Higgs field and boson did ''not'' exist within the expected mass range would have also been significant.

=== Particle physics === ==== Validation of the Standard Model ==== The Higgs boson validates the [[Standard Model]] mechanism of [[mass generation]] for the weak bosons, and can provide masses to the fermions. As more precise measurements of its properties are made, more advanced extensions may be suggested or excluded. As experimental means to measure the Higgs field behaviour and interactions are developed, this fundamental field may be better understood. If the Higgs boson had not been discovered, the Standard Model would have needed to be modified or superseded.

Related to this, it is a widely held belief among many physicists that there is likely to be "new" [[physics beyond the Standard Model]], and the Standard Model will at some point be extended or superseded. The discovery of the Higgs boson, as well as the many measured collisions occurring at the LHC, provide physicists with a sensitive tool to search their data for any evidence of the failure of the Standard Model, and might provide considerable evidence to guide researchers into future theoretical developments.

==== Symmetry breaking of the electroweak interaction ==== Below an extremely high temperature, [[electroweak symmetry breaking]] causes the [[electroweak interaction]] to manifest in part as the short-ranged [[weak force]], which is carried by massive [[gauge boson]]s. In the [[Chronology of the universe|history of the universe]], electroweak symmetry breaking is believed to have happened at about {{nowrap|1 [[picosecond]] (10−12 s)}} after the [[Big Bang]], when the universe was at a temperature {{val|159.5|1.5|u=[[Electronvolt#Temperature|GeV/''k''B]]}}.<ref> {{cite journal |last1 = D'Onofrio |first1=Michela |last2 = Rummukainen |first2=Kari |title = Standard model cross-over on the lattice |journal = Phys. Rev. |volume = D93 |year = 2016 |number = 2 |article-number = 025003 |doi = 10.1103/PhysRevD.93.025003 |arxiv = 1508.07161 |bibcode = 2016PhRvD..93b5003D |s2cid = 119261776 }}</ref> This symmetry breaking is required for [[atom]]s and other structures to form, as well as for nuclear reactions in stars, such as the [[Sun]]. The Higgs field is responsible for this symmetry breaking.

==== Particle mass acquisition ==== The Higgs field is pivotal in [[Mass generation|generating the masses]] of [[quark]]s and charged [[leptons]] (through Yukawa coupling) and the [[W and Z bosons|W and Z gauge bosons]] (through the Higgs mechanism), although it was the generation of mass for the weak bosons which is the most significant factor – providing terms in the Standard Model Lagrangian that allow for the generation of fermion masses, was a useful, but less significant by product. The fermion masses must be entered by hand, essentially determining the relative strength of the coupling of the fermion to the Higgs field.

The Higgs field does not "create" mass [[creatio ex nihilo|out of nothing]], nor is the Higgs field responsible for the mass of all particles. For example, approximately 99% of the mass of [[baryon]]s ([[composite particle]]s such as the [[proton]] and [[neutron]]) is due instead to [[quantum chromodynamics binding energy|quantum chromodynamic binding energy]], which is the sum of the [[kinetic energy|kinetic energies]] of quarks and the [[gluon energy|energies]] of the massless [[gluon]]s mediating the [[strong interaction]] inside the baryons.<ref>{{cite web |url=http://cms.web.cern.ch/news/why-would-i-care-about-higgs-boson |title=Why would I care about the Higgs boson? |last=Rao |first=Achintya |date=2 July 2012 |publisher=CERN |website=CMS Public Website |access-date=18 July 2012 |archive-date=9 July 2012 |archive-url=https://web.archive.org/web/20120709001636/http://cms.web.cern.ch/news/why-would-i-care-about-higgs-boson |url-status=live }}</ref> In Higgs-based theories, the property of "mass" is a manifestation of [[potential energy]] transferred to fundamental particles when they interact ("couple") with the Higgs field.<ref>{{cite book |last=Jammer |first=Max |url=https://archive.org/details/conceptsmasscont00jamm_737 |title=Concepts of Mass in Contemporary Physics and Philosophy |publisher=Princeton University Press |year=2000 |isbn=978-0-691-01017-5 |location=Princeton, New Jersey |pages=[https://archive.org/details/conceptsmasscont00jamm_737/page/n173 162]–163 |url-access=limited}}, who provides many references in support of this statement.</ref>

==== Scalar fields and extension of the Standard Model ==== The Higgs field is the only scalar (spin-0) field to be detected; all the other fundamental fields in the Standard Model are spin-{{sfrac| 1 |2}} [[fermions]] or spin-1 bosons.{{efn| The statement excludes spin-0 [[mesons]], such as the [[pion]], since they are known to be composites of pairs of spin-{{sfrac| 1 |2}} fermions. }} According to [[Rolf-Dieter Heuer]], director general of CERN when the Higgs boson was discovered, this existence proof of a scalar field is almost as important as the Higgs's role in determining the mass of other particles. It suggests that other hypothetical scalar fields suggested by other theories, from the [[inflaton]] to [[quintessence (physics)|quintessence]], could perhaps exist as well.<ref> {{cite news |last=Dvorsky |first=George |date=12 August 2013 |title=Is there a link between the Higgs boson and dark energy? |website=io9.gizmodo.com |url=https://io9.gizmodo.com/is-there-a-link-between-the-higgs-boson-and-dark-energy-1109308709 |access-date=1 March 2018 |url-status=live |archive-url=https://web.archive.org/web/20180301164529/https://io9.gizmodo.com/is-there-a-link-between-the-higgs-boson-and-dark-energy-1109308709 |archive-date=1 March 2018 }} </ref><ref> {{cite news |title=What universe is this, anyway? |language=en |date=2 April 2014 |website=[[National Public Radio]] (NPR.org) |url=https://www.npr.org/sections/13.7/2014/04/02/297853038/what-universe-is-this-anyway |access-date=1 March 2018 |url-status=live |archive-url=https://web.archive.org/web/20180301224950/https://www.npr.org/sections/13.7/2014/04/02/297853038/what-universe-is-this-anyway |archive-date=1 March 2018 }} </ref>

=== Cosmology === ==== Inflaton ==== There has been considerable scientific research on possible links between the Higgs field and the [[inflaton]]{{snd}}a hypothetical field suggested as the explanation for the [[metric expansion of space|expansion of space]] during [[Chronology of the universe|the first fraction of a second]] of the [[universe]] (known as the "[[inflationary epoch]]"). Some theories suggest that a fundamental scalar field might be responsible for this phenomenon; the Higgs field is such a field, and its existence has led to papers analysing whether it could also be the ''inflaton'' responsible for this [[exponential growth|exponential]] expansion of the universe during the [[Big Bang]]. Such theories are highly tentative and face significant problems related to [[Unitarity (physics)|unitarity]], but may be viable if combined with additional features such as large non-minimal coupling, a [[Brans–Dicke theory|Brans–Dicke]] scalar, or other "new" physics, and they have received treatments suggesting that Higgs inflation models are still of interest theoretically.

==== Nature of the universe, and its possible fates ==== [[File:Higgs-Mass-MetaStability.svg|upright=1.6|thumb|Diagram showing the Higgs boson and [[top quark]] masses, which could indicate whether our universe is stable, or a [[Metastability|long-lived 'bubble']]. As of 2012, the 2{{mvar|σ}} ellipse based on [[Tevatron]] and LHC data still allows for both possibilities.<ref name="Alekhin 2012">{{cite journal |last1=Alekhin |first1=S. |last2=Djouadi |first2=A. |last3=Moch |first3=S. |date=13 August 2012 |title=The top quark and Higgs boson masses and the stability of the electroweak vacuum |journal=Physics Letters B |volume=716 |issue=1 |pages=214–219 |arxiv=1207.0980 |bibcode=2012PhLB..716..214A |doi=10.1016/j.physletb.2012.08.024 |s2cid=28216028}}</ref>]] In the Standard Model, there exists the possibility that the underlying state of our universe – known as the "vacuum" – is [[metastability|long-lived, but not completely stable]]. In this scenario, the universe as we know it could effectively be destroyed by collapsing into a [[False vacuum decay|more stable vacuum state]].<ref name="turnerwilczek">{{cite journal |last1=Turner |first1=M. S. |last2=Wilczek |first2=F. |year=1982 |title=Is our vacuum metastable? |journal=Nature |volume=298 |issue=5875 |pages=633–634 |bibcode=1982Natur.298..633T |doi=10.1038/298633a0 |s2cid=4274444}}</ref><ref name="colemandeluccia">{{cite journal |year=1980 |title=Gravitational effects on and of vacuum decay |journal=Physical Review |volume=D21 |issue=12 |pages=3305–3315 |bibcode=1980PhRvD..21.3305C |doi=10.1103/PhysRevD.21.3305 |author1=Coleman, S. |author2=de Luccia, F. |osti=1445512|s2cid=1340683 }}</ref><ref>{{cite journal |year=1976 |title=Lifetime and decay of excited vacuum states |journal=Phys. Rev. D |volume=14 |issue=12 |pages=3568–3573 |bibcode=1976PhRvD..14.3568S |doi=10.1103/PhysRevD.14.3568 |author=Stone, M.}}</ref><ref>{{cite journal |author=Frampton |first=P. H. |year=1976 |title=Vacuum Instability and Higgs Scalar Mass |journal=Physical Review Letters |volume=37 |issue=21 |pages=1378–1380 |bibcode=1976PhRvL..37.1378F |doi=10.1103/PhysRevLett.37.1378}}</ref><ref>{{cite journal |author=Frampton |first=P. H. |year=1977 |title=Consequences of Vacuum Instability in Quantum Field Theory |journal=Phys. Rev. D |volume=15 |issue=10 |pages=2922–2928 |bibcode=1977PhRvD..15.2922F |doi=10.1103/PhysRevD.15.2922}}</ref> This was sometimes misreported as the Higgs boson "ending" the universe.{{efn|1=For example: The [[Huffington Post]] / [[Reuters]],<ref>{{cite news |author=Klotz, Irene |editor1=Adams, David |editor2=Eastham, Todd |title=Universe has finite lifespan, Higgs boson calculations suggest |url=https://huffingtonpost.com/2013/02/19/universe-lifespan-finite-unstable-higgs-boson_n_2713053.html |access-date=21 February 2013 |newspaper=Huffington Post |date=18 February 2013 |agency=Reuters |quote=Earth will likely be long gone before any Higgs boson particles set off an apocalyptic assault on the universe |archive-date=20 February 2013 |archive-url=https://web.archive.org/web/20130220141633/http://www.huffingtonpost.com/2013/02/19/universe-lifespan-finite-unstable-higgs-boson_n_2713053.html |url-status=live }}</ref> and others.<ref>{{cite web |last=Hoffman |first=Mark |title=Higgs boson will destroy the universe, eventually |url=http://www.scienceworldreport.com/articles/5038/20130219/higgs-boson-instability-will-destroy-universe-eventually.htm |access-date=21 February 2013 |website=Science World Report |date=19 February 2013 |archive-date=11 June 2019 |archive-url=https://web.archive.org/web/20190611181953/https://www.scienceworldreport.com/articles/5038/20130219/higgs-boson-instability-will-destroy-universe-eventually.htm |url-status=live }}</ref>}} If the masses of the Higgs boson and [[top quark]] are known more precisely, and the Standard Model provides an accurate description of particle physics up to extreme energies of the [[Planck units#Planck scale|Planck scale]], then it is possible to calculate whether the vacuum is stable or merely long-lived.<ref>{{cite journal |last1=Ellis |first1=J. |last2=Espinosa |first2=J. R. |last3=Giudice |first3=G. F. |last4=Hoecker |first4=A. |last5=Riotto |first5=A. |year=2009 |title=The Probable Fate of the Standard Model |journal=Physics Letters B |volume=679 |issue=4 |pages=369–375 |arxiv=0906.0954 |bibcode=2009PhLB..679..369E |doi=10.1016/j.physletb.2009.07.054 |s2cid=17422678}}</ref><ref>{{cite journal |last=Masina |first=Isabella |date=12 February 2013 |title=Higgs boson and top quark masses as tests of electroweak vacuum stability |journal=Phys. Rev. D |volume=87 |issue=5 |article-number=053001 |arxiv=1209.0393 |bibcode=2013PhRvD..87e3001M |doi=10.1103/PhysRevD.87.053001 |s2cid=118451972}}</ref><ref>{{cite journal |first1=Dario |last1=Buttazzo |first2=Giuseppe |last2=Degrassi |first3=Pier Paolo |last3=Giardino |first4=Gian F. |last4=Giudice |first5=Filippo |last5=Sala |first6=Alberto |last6=Salvio |first7=Alessandro |last7=Strumia |year=2013 |title=Investigating the near-criticality of the Higgs boson |url=http://inspirehep.net/record/1242456 |journal=JHEP |volume=2013 |issue=12 |page=089 |arxiv=1307.3536 |bibcode=2013JHEP...12..089B |doi=10.1007/JHEP12(2013)089 |s2cid=54021743 |access-date=25 June 2014 |archive-date=28 August 2014 |archive-url=https://web.archive.org/web/20140828091031/http://inspirehep.net/record/1242456/ |url-status=live }}</ref> A Higgs mass of {{val|125|–|127|u=GeV/c2}} seems to be extremely close to the boundary for stability, but a definitive answer requires much more precise measurements of the [[pole mass]] of the top quark.<ref name="Alekhin 2012"/> New physics can change this picture.<ref name="Salvio 2015">{{cite journal |last=Salvio |first=Alberto |date=9 April 2015 |title=A simple, motivated completion of the Standard Model below the Planck scale: Axions and right-handed neutrinos |journal=Physics Letters B |volume=743 |pages=428–434 |arxiv=1501.03781 |bibcode=2015PhLB..743..428S |doi=10.1016/j.physletb.2015.03.015 |s2cid=119279576}}</ref>

If measurements of the Higgs boson suggest that our universe lies within a [[False vacuum decay|false vacuum]] of this kind, then it would imply{{snd}}more than likely in many billions of years<ref name="Boyle">{{cite news |url=http://cosmiclog.nbcnews.com/_news/2013/02/18/17006552-will-our-universe-end-in-a-big-slurp-higgs-like-particle-suggests-it-might?lite |title=Will our universe end in a 'big slurp'? Higgs-like particle suggests it might |last=Boyle |first=Alan |date=19 February 2013 |website=NBC News' Cosmic blog |access-date=21 February 2013 |quote=[T]he bad news is that its mass suggests the universe will end in a fast-spreading bubble of doom. The good news? It'll probably be tens of billions of years. |archive-date=21 February 2013 |archive-url=https://web.archive.org/web/20130221030545/http://cosmiclog.nbcnews.com/_news/2013/02/18/17006552-will-our-universe-end-in-a-big-slurp-higgs-like-particle-suggests-it-might?lite |url-status=live }} The article quotes [[Fermilab]]'s Joseph Lykken: "[T]he parameters for our universe, including the Higgs [and top quark's masses] suggest that we're just at the edge of stability, in a "metastable" state. Physicists have been contemplating such a possibility for more than 30 years. Back in 1982, physicists Michael Turner and Frank Wilczek wrote in ''Nature'' that "without warning, a bubble of true vacuum could nucleate somewhere in the universe and move outwards ..."</ref>{{efn|The bubble's effects would be expected to propagate across the universe at the speed of light from wherever it occurred. However space is vast – with even [[Andromeda Galaxy|the nearest galaxy]] being over 2 million [[light years]] from us, and others being many billions of light years distant, so the effect of such an event would be unlikely to arise here for billions of years after first occurring.<ref name="Boyle"/><ref>{{cite web |last=Peralta |first=Eyder |title=If Higgs boson calculations are right, a catastrophic 'bubble' could end universe |url=https://www.npr.org/blogs/thetwo-way/2013/02/19/172422921/if-higgs-boson-calculations-are-right-a-catastrophic-bubble-could-end-universe |access-date=21 February 2013 |publisher=NPR News |website=The Two-Way |date=2013-02-19 |archive-date=21 February 2013 |archive-url=https://web.archive.org/web/20130221005726/http://www.npr.org/blogs/thetwo-way/2013/02/19/172422921/if-higgs-boson-calculations-are-right-a-catastrophic-bubble-could-end-universe |url-status=live }} Article cites [[Fermilab]]'s Joseph Lykken: "The bubble forms through an unlikely quantum fluctuation, at a random time and place," Lykken tells us. "So in principle it could happen tomorrow, but then most likely in a very distant galaxy, so we are still safe for billions of years before it gets to us."</ref>}}{{snd}}that the universe's forces, particles, and structures could cease to exist as we know them (and be replaced by different ones), if a true vacuum happened to [[Nucleation|nucleate]].<ref name="Boyle"/>{{efn|If the Standard Model is valid, then the particles and forces we observe in our universe exist as they do, because of underlying quantum fields. Quantum fields can have states of differing stability, including 'stable', 'unstable' and '[[Metastability|metastable]]' states (the latter remain stable unless sufficiently [[Perturbation theory (quantum mechanics)|perturbed]]). If a more stable vacuum state were able to arise, then existing particles and forces would no longer arise as they presently do. Different particles or forces would arise from (and be shaped by) whatever new quantum states arose. The world we know depends upon these particles and forces, so if this happened, everything around us, from [[subatomic particle]]s to [[Galaxy|galaxies]], and all [[fundamental interaction|fundamental forces]], would be reconstituted into new fundamental particles and forces and structures. The universe would potentially lose all of its present structures and become inhabited by new ones (depending upon the exact states involved) based upon the same quantum fields.}} It also suggests that the Higgs [[Coupling (physics)|self-coupling]] {{mvar|λ}} and its {{mvar|β}}{{mvar|λ}} function could be very close to zero at the Planck scale, with "intriguing" implications, including theories of gravity and Higgs-based inflation.<ref name="Alekhin 2012"/>{{rp|218}}<ref>{{cite journal |last1=Bezrukov |first1=F. |last2=Shaposhnikov |first2=M. |date=24 January 2008 |title=The Standard Model Higgs boson as the inflaton |journal=Physics Letters B |volume=659 |issue=3 |pages=703–706 |arxiv=0710.3755 |bibcode=2008PhLB..659..703B |doi=10.1016/j.physletb.2007.11.072|s2cid=14818281 }}</ref><ref>{{cite journal |last=Salvio |first=Alberto |date=9 August 2013 |title=Higgs Inflation at NNLO after the Boson Discovery |url=http://inspirehep.net/record/1247471 |journal=Physics Letters B |volume=727 |issue=1–3 |pages=234–239 |arxiv=1308.2244 |bibcode=2013PhLB..727..234S |doi=10.1016/j.physletb.2013.10.042 |s2cid=56544999 |access-date=25 June 2014 |archive-date=26 January 2016 |archive-url=https://web.archive.org/web/20160126044115/http://inspirehep.net/record/1247471 |url-status=live }}</ref> A future electron–positron collider would be able to provide the precise measurements of the top quark needed for such calculations.<ref name="Alekhin 2012"/>

==== Vacuum energy and the cosmological constant ==== {{further|Zero-point energy|Vacuum state}}More speculatively, the Higgs field has also been proposed as the [[Vacuum energy|energy of the vacuum]], which at the extreme energies of the first moments of the [[Big Bang]] caused the universe to be a kind of featureless symmetry of undifferentiated, extremely high energy. In this kind of speculation, the single unified field of a [[Grand Unified Theory]] is identified as (or modelled upon) the Higgs field, and it is through successive symmetry breakings of the Higgs field, or some similar field, at [[phase transition]]s that the presently known forces and fields of the universe arise.<ref>{{cite news |last=Cole |first=K. C. |date=14 December 2000 |title=One Thing Is Perfectly Clear: Nothingness Is Perfect |url=https://www.latimes.com/archives/la-xpm-2000-dec-14-me-65457-story.html |url-status=live |archive-url=https://web.archive.org/web/20220125094442/https://www.latimes.com/archives |archive-date=25 January 2022 |access-date=17 January 2013 |newspaper=[[Los Angeles Times]] |quote=[T]he Higgs' influence (or the influence of something like it) could reach much further. For example, something like the Higgs—if not exactly the Higgs itself—may be behind many other unexplained "broken symmetries" in the universe as well ... In fact, something very much like the Higgs may have been behind the collapse of the symmetry that led to the Big Bang, which created the universe. When the forces first began to separate from their primordial sameness—taking on the distinct characters they have today—they released energy in the same way as water releases energy when it turns to ice. Except in this case, the freezing packed enough energy to blow up the universe. ... However it happened, the moral is clear: Only when the perfection shatters can everything else be born.}}</ref>

The relationship (if any) between the Higgs field and the observed [[Vacuum energy|vacuum energy density]] of the universe has also come under scientific study. As observed, the vacuum energy density is extremely close to zero, but the energy densities predicted from the Higgs field, supersymmetry, and other theories are typically many orders of magnitude larger. It is unclear how these should be reconciled. This [[cosmological constant]] problem remains a major [[Unanswered questions in physics|unanswered problem]] in physics.

== History == === Theorisation === {{See also|1964 PRL symmetry breaking papers|Higgs mechanism|History of quantum field theory}} {| class="wikitable" style="float:right; margin:0 0 1em 1em; font-size:85%; width:354px;" |- | {{nowrap|[[File:AIP-Sakurai-best.JPG|x150px]]  [[File:Higgs, Peter (1929) cropped.jpg|x150px|upright=0.7]]}} The six authors of the [[1964 PRL symmetry breaking papers|1964 PRL papers]], who received the 2010 [[Sakurai Prize|J. J. Sakurai Prize]] for their work; from left to right: [[T. W. B. Kibble|Kibble]], [[Gerald Guralnik|Guralnik]], [[C. R. Hagen|Hagen]], [[François Englert|Englert]], [[Robert Brout|Brout]]; ''right image:'' [[Peter Higgs|Higgs]]. |} Particle physicists study [[matter]] made from [[fundamental particle]]s whose interactions are mediated by exchange particles{{snd}}[[gauge boson]]s{{snd}}acting as [[force carrier]]s. At the beginning of the 1960s a number of these particles had been discovered or proposed, along with theories suggesting how they relate to each other, some of which had already been reformulated as [[quantum field theory|field theories]] in which the objects of study are not particles and forces, but [[quantum field]]s and their [[Symmetry (physics)|symmetries]].<ref name="Carroll2012">{{cite book |author=Carroll |first=Sean |title=[[The Particle at the End of the Universe: How the Hunt for the Higgs Boson Leads Us to the Edge of a New World]] |publisher=Penguin Group US |year=2012 |isbn=978-1-101-60970-5}}</ref>{{rp|150}} However, attempts to produce quantum field models for two of the four known [[fundamental interaction|fundamental forces]] – the [[electromagnetic force]] and the [[weak nuclear force]] – and then to [[Unified field theory|unify these interactions]], were still unsuccessful.

One known problem was that [[gauge invariance|gauge invariant]] approaches, including [[non-abelian gauge theory|non-abelian]] models such as [[Yang–Mills theory]] (1954), which held great promise for unified theories, also seemed to predict known massive particles as massless.<ref name=woit>{{cite web |last=Woit |first=Peter |title=The Anderson–Higgs Mechanism |url=http://www.math.columbia.edu/~woit/wordpress/?p=3282 |publisher=Dr. Peter Woit (Senior Lecturer in Mathematics [[Columbia University]] and Ph.D. particle physics) |access-date=12 November 2012 |date=13 November 2010 |archive-date=23 November 2012 |archive-url=https://web.archive.org/web/20121123213726/http://www.math.columbia.edu/~woit/wordpress/?p=3282 |url-status=live }}</ref> [[Goldstone's theorem]], relating to [[continuous symmetry|continuous symmetries]] within some theories, also appeared to rule out many obvious solutions,<ref>{{cite journal |last1=Goldstone |first1=J. |last2=Salam |first2=Abdus |last3=Weinberg |first3=Steven |year=1962 |title=Broken Symmetries |journal=Physical Review |volume=127 |issue=3 |pages=965–970 |doi=10.1103/PhysRev.127.965 |bibcode=1962PhRv..127..965G}}</ref> since it appeared to show that zero-mass particles known as [[Goldstone boson]]s would also have to exist that simply were "not seen".<ref name="Guralnik 2011">{{cite arXiv |last=Guralnik |first=G. S. |year=2011 |title=The Beginnings of Spontaneous Symmetry Breaking in Particle Physics |eprint=1110.2253 |class=physics.hist-ph}}</ref> According to [[Gerald Guralnik|Guralnik]], physicists had "no understanding" how these problems could be overcome.<ref name="Guralnik 2011"/>

[[File:Nobel Prize 24 2013.jpg|thumb|upright=0.7|Nobel Prize Laureate [[Peter Higgs]] in Stockholm, December 2013]] Particle physicist and mathematician Peter Woit summarised the state of research at the time:{{blockquote|Yang and Mills work on [[non-abelian gauge theory]] had one huge problem: in [[perturbation theory]] it has massless particles which don't correspond to anything we see. One way of getting rid of this problem is now fairly well understood, the phenomenon of [[color confinement|confinement]] realized in [[quantum chromodynamics|QCD]], where the strong interactions get rid of the massless "gluon" states at long distances. By the very early sixties, people had begun to understand another source of massless particles: spontaneous symmetry breaking of a continuous symmetry. What [[Philip Warren Anderson|Philip Anderson]] realized and worked out in the summer of 1962 was that, when you have ''both'' gauge symmetry ''and'' spontaneous symmetry breaking, the massless Nambu–Goldstone mode [which gives rise to Goldstone bosons] can combine with the massless gauge field modes [which give rise to massless gauge bosons] to produce a physical massive vector field [gauge bosons with mass]. This is what happens in [[superconductivity]], a subject about which Anderson was (and is) one of the leading experts.<ref name="woit" /> ''[text condensed]''}}

The Higgs mechanism is a process by which [[vector boson]]s can acquire [[rest mass]] ''without'' [[explicit symmetry breaking|explicitly breaking gauge invariance]], as a byproduct of [[spontaneous symmetry breaking]].<ref name="scholarpedia">{{cite journal |last=Kibble |first=T.W.B. |year=2009 |title=Englert–Brout–Higgs–Guralnik–Hagen–Kibble Mechanism |journal=[[Scholarpedia]] |volume=4 |issue=1 |page=6441 |doi=10.4249/scholarpedia.6441 |bibcode = 2009SchpJ...4.6441K |doi-access=free}}</ref><ref name="scholarpedia_a">{{cite journal |last=Kibble |first=T.W.B. |title=History of Englert–Brout–Higgs–Guralnik–Hagen–Kibble Mechanism (history) |journal=[[Scholarpedia]] |volume=4 |issue=1 |page=8741 |doi=10.4249/scholarpedia.8741 |bibcode = 2009SchpJ...4.8741K |year=2009 |doi-access=free }}</ref> Initially, the mathematical theory behind spontaneous symmetry breaking was conceived and published within particle physics by [[Yoichiro Nambu]] in 1960<ref name="nambu nobel">{{cite web |url=https://www.nobelprize.org/nobel_prizes/physics/laureates/2008 |title=The Nobel Prize in Physics 2008 |archive-url=https://web.archive.org/web/20090113093401/https://www.nobelprize.org/nobel_prizes/physics/laureates/2008 |archive-date=13 January 2009 |website=Nobelprize.org }}</ref> (and [[Stueckelberg action|somewhat anticipated]] by [[Ernst Stueckelberg]] in 1938<ref>{{Cite journal|arxiv=hep-th/0304245|doi=10.1142/S0217751X04019755|title=The Stueckelberg Field|year=2004|last1=Ruegg|first1=Henri|last2=Ruiz-Altaba|first2=Martí|journal=International Journal of Modern Physics A|volume=19|issue=20|pages=3265–3347|bibcode=2004IJMPA..19.3265R|s2cid=7017354}}</ref>), and the concept that such a mechanism could offer a possible solution for the "mass problem" was originally suggested in 1962 by Philip Anderson, who had previously written papers on broken symmetry and its outcomes in superconductivity.<ref>{{plain link|url=http://publish.aps.org/search?q=&clauses%5b%5d%5boperator%5d=AND&clauses%5b%5d%5bfield%5d=author&clauses%5b%5d%5bvalue%5d=anderson&clauses%5b%5d%5boperator%5d=AND&clauses%5b%5d%5bfield%5d=abstitle&clauses%5b%5d%5bvalue%5d=&clauses%5b%5d%5boperator%5d=AND&clauses%5b%5d%5bfield%5d=all&clauses%5b%5d%5bvalue%5d=symmetry&per_page=25|name=List of Anderson 1958–1959 papers referencing 'symmetry'}}, at APS Journals.{{dead link|date=August 2018}}</ref> Anderson concluded in his 1963 paper on the Yang–Mills theory, that "considering the superconducting analog ... [t]hese two types of bosons seem capable of canceling each other out ... leaving finite mass bosons"),<ref name="MyLifeAsABoson">{{cite web |last=Higgs |first=Peter |date=24 November 2010 |title=My Life as a Boson |url=http://www.kcl.ac.uk/nms/depts/physics/news/events/MyLifeasaBoson.pdf |archive-url=https://web.archive.org/web/20131104043410/http://www.kcl.ac.uk/nms/depts/physics/news/events/MyLifeasaBoson.pdf |archive-date=4 November 2013 |access-date=17 January 2013 |publisher=King's College |pages=4–5 |location=London}}{{snd}}Talk given by Peter Higgs at King's College, London, England, expanding on a paper originally presented in 2001. The original 2001 paper may be found in: {{cite book |last=Higgs |first=Peter |url=https://books.google.com/books?id=ONhnbpq00xIC&pg=PR11 |title=2001 A Spacetime Odyssey: Proceedings of the Inaugural Conference of the Michigan Center for Theoretical Physics |date=25 May 2001 |publisher=World Scientific |isbn=978-9-8123-8231-3 |editor=Michael J. Duff |location=Ann Arbor, Michigan |pages=86–88 |chapter=My Life as a Boson: The Story of 'The Higgs' |access-date=17 January 2013 |editor2=James T. Liu |chapter-url=https://books.google.com/books?id=ONhnbpq00xIC&pg=PA86 |archive-url=https://web.archive.org/web/20220125094455/https://books.google.com/books?id=ONhnbpq00xIC&pg=PR11 |archive-date=25 January 2022 |url-status=live |name-list-style=amp}}</ref><ref name=Anderson-1963>{{cite journal |last1=Anderson |first1=P. |date=April 1963 |title=Plasmons, gauge invariance and mass |journal=Physical Review |volume=130 |issue=1 |pages=439–442 |bibcode=1963PhRv..130..439A |doi=10.1103/PhysRev.130.439}}</ref> and in March 1964, [[Abraham Klein (physicist)|Abraham Klein]] and [[Benjamin W. Lee|Benjamin Lee]] showed that Goldstone's theorem could be avoided this way in at least some non-relativistic cases, and speculated it might be possible in truly relativistic cases.<ref name="Klein-Lee-1964"> {{cite journal |last1=Klein |first1=Abraham |author1-link=Abraham Klein (physicist) |last2=Lee |first2=Benjamin W. |author2-link=Benjamin W. Lee |date=March 1964 |title=Does Spontaneous Breakdown of Symmetry Imply Zero-Mass Particles? |journal=Physical Review Letters |volume=12 |issue=10 |pages=266–268 |bibcode=1964PhRvL..12..266K |doi=10.1103/PhysRevLett.12.266}} </ref>

These approaches were quickly developed into a full [[Special relativity|relativistic]] model, independently and almost simultaneously, by three groups of physicists: by [[François Englert]] and [[Robert Brout]] in August 1964;<ref name="eb64"> {{cite journal |last1=Englert |first1=François |author1-link=François Englert |last2=Brout |first2=Robert |author2-link=Robert Brout |year=1964 |title=Broken Symmetry and the Mass of Gauge Vector Mesons |journal=[[Physical Review Letters]] |volume=13 |issue=9 |pages=321–323 |doi=10.1103/PhysRevLett.13.321 |bibcode=1964PhRvL..13..321E |doi-access=free }}</ref> by [[Peter Higgs]] in October 1964;<ref name="higgs64"> {{cite journal |first=Peter |last=Higgs |year=1964 |title=Broken Symmetries and the Masses of Gauge Bosons |journal=[[Physical Review Letters]] |volume=13 |issue=16 |pages=508–509 |doi=10.1103/PhysRevLett.13.508 |bibcode=1964PhRvL..13..508H |doi-access=free }}</ref> and by [[Gerald Guralnik]], [[C. R. Hagen|Carl Hagen]], and [[T. W. B. Kibble|Tom Kibble]] (GHK) in November 1964.<ref name="ghk64"> {{cite journal |last1=Guralnik |first1=Gerald |author-link=Gerald Guralnik |last2=Hagen |first2=C. R. |author-link2=C. R. Hagen |last3=Kibble |first3=T. W. B. |author-link3=T. W. B. Kibble |year=1964 |title=Global Conservation Laws and Massless Particles |journal=[[Physical Review Letters]] |volume=13 |issue=20 |pages=585–587 |doi=10.1103/PhysRevLett.13.585 |bibcode=1964PhRvL..13..585G |doi-access=free }}</ref> Higgs also wrote a short, but important,<ref name="scholarpedia" /> response published in September 1964 to an objection by [[Walter Gilbert|Gilbert]],<ref name="higgs64note"> {{cite journal |first=Peter |last=Higgs |year=1964 |title=Broken symmetries, massless particles, and gauge fields |journal=[[Physics Letters]] |volume=12 |issue=2 |pages=132–133 |bibcode=1964PhL....12..132H |doi=10.1016/0031-9163(64)91136-9 }}</ref> which showed that if calculating within the radiation gauge, Goldstone's theorem and Gilbert's objection would become inapplicable.{{efn|name=GoldstoneNote}} Higgs later described Gilbert's objection as prompting his own paper.<ref>{{cite report |last=Higgs |first=Peter |date=24 November 2010 |title=My Life as a Boson |series=Talk given by Peter Higgs at King's College, London, 24 November 2010 |publisher=[[King's College, London]] |url=http://www.kcl.ac.uk/nms/depts/physics/news/events/MyLifeasaBoson.pdf |access-date=17 January 2013 |archive-url=https://web.archive.org/web/20131104043410/http://www.kcl.ac.uk/nms/depts/physics/news/events/MyLifeasaBoson.pdf |archive-date=4 November 2013 |quote=Gilbert ... wrote a response to [Klein and Lee's paper] saying 'No, you cannot do that in a relativistic theory. You cannot have a preferred unit time-like vector like that.' This is where I came in, because the next month was when I responded to Gilbert's paper by saying 'Yes, you can have such a thing' but only in a gauge theory with a gauge field coupled to the current.}}</ref> Properties of the model were further considered by Guralnik in 1965,<ref>{{cite journal |author=Guralnik |first=G. S. |year=2011 |title=Gauge invariance and the Goldstone theorem{{snd}} 1965 Feldafing talk |journal=[[Modern Physics Letters A]] |volume=26 |issue=19 |pages=1381–1392 |arxiv=1107.4592 |bibcode=2011MPLA...26.1381G |doi=10.1142/S0217732311036188 |s2cid=118500709}}</ref> by Higgs in 1966,<ref>{{cite journal |first=Peter |last=Higgs |year=1966 |title=Spontaneous symmetry breakdown without massless bosons |journal=[[Physical Review]] |volume=145 |issue=4 |pages=1156–1163 |doi=10.1103/PhysRev.145.1156 |doi-access=free |bibcode=1966PhRv..145.1156H}}</ref> by Kibble in 1967,<ref>{{Cite journal |first=Tom |last=Kibble |year=1967 |title=Symmetry Breaking in Non-Abelian Gauge Theories |journal=[[Physical Review]] |volume=155 |issue=5 |pages=1554–1561 |doi=10.1103/PhysRev.155.1554|bibcode = 1967PhRv..155.1554K }}</ref> and further by GHK in 1967.<ref>{{cite journal |last1=Guralnik |first1=G. S. |last2=Hagen |first2=C. R. |last3=Kibble |first3=T. W. B. |year=1967 |title=Broken symmetries and the Goldstone theorem |url=http://www.physics.princeton.edu/~mcdonald/examples/EP/guralnik_ap_2_567_67.pdf |journal=Advances in Physics |volume=2 |page=567 |archive-url=https://web.archive.org/web/20150924072804/http://www.physics.princeton.edu/~mcdonald/examples/EP/guralnik_ap_2_567_67.pdf |archive-date=24 September 2015 |access-date=16 September 2014}}</ref> The original three 1964 papers demonstrated that when a [[gauge theory]] is combined with an additional charged scalar field that spontaneously breaks the symmetry, the gauge bosons may consistently acquire a finite mass.<ref name=scholarpedia/><ref name=scholarpedia_a/><ref name=prl> {{cite journal |url=http://prl.aps.org/50years/milestones#1964 |title=Letters from the Past – A PRL Retrospective |journal=[[Physical Review Letters]] |date=12 February 2014 |access-date=7 May 2008 |archive-date=10 January 2010 |archive-url=https://archive.today/20100110134128/http://prl.aps.org/50years/milestones#1964 |url-status=live }} </ref> In 1967, [[Steven Weinberg]]<ref> {{cite journal | author=Weinberg, S. | year=1967 | title=A model of leptons | journal=[[Physical Review Letters]] | volume=19 | issue=21 | pages=1264–1266 | doi=10.1103/PhysRevLett.19.1264 | bibcode=1967PhRvL..19.1264W | doi-access=free }} </ref> and [[Abdus Salam]]<ref> {{cite conference | author=Salam, A. | editor=Svartholm, N. | year=1968 | book-title=Elementary Particle Physics: Relativistic Groups and Analyticity | page=367 | conference=Eighth Nobel Symposium | publisher=Almquvist and Wiksell | location=Stockholm, SV }} </ref> independently showed how a Higgs mechanism could be used to break the electroweak symmetry of [[Sheldon Glashow]]'s [[electroweak theory|unified model for the weak and electromagnetic interactions]],<ref> {{cite journal |author=Glashow |first=S. L. |year=1961 |title=Partial-symmetries of weak interactions |journal=[[Nuclear Physics (journal)|Nuclear Physics]] |volume=22 |issue=4 |pages=579–588 |bibcode=1961NucPh..22..579G |doi=10.1016/0029-5582(61)90469-2}} </ref> (itself an extension of work by [[Julian Schwinger|Schwinger]]), forming what became the [[Standard Model]] of particle physics. Weinberg was the first to observe that this would also provide mass terms for the fermions.<ref name="Ellis2012"> {{cite arXiv |first1=John |last1=Ellis |first2=Mary K. |last2=Gaillard |first3=Dimitri V. |last3=Nanopoulos |year=2012 |title=A historical profile of the Higgs boson |eprint=1201.6045 |class=hep-ph }} </ref>{{efn|1=A field with the "Mexican hat" potential <math> V(\phi) = \mu^2\phi^2 + \lambda\phi^4 </math> and <math> \mu^2 < 0 </math> has a minimum not at zero but at some non-zero value <math>\phi_0 ~.</math> By expressing the action in terms of the field <math>\tilde \phi = \phi-\phi_0</math> (where <math>\phi_0</math> is a constant independent of position), we find the Yukawa term has a component <math>g\phi_0 \bar\psi\psi ~.</math> Since both {{mvar|g}} and <math>\phi_0</math> are constants, this looks exactly like the mass term for a fermion of mass <math>g\phi_0</math>. The field <math>\tilde\phi</math> is then the [[Higgs field]].}}

At first, these seminal papers on spontaneous breaking of gauge symmetries were largely ignored, because it was widely believed that the (non-Abelian gauge) theories in question were a dead-end, and in particular that they could not be [[renormalizable|renormalised]]. In 1971–72, [[Martinus Veltman]] and [[Gerard 't Hooft]] proved renormalisation of Yang–Mills was possible in two papers covering massless, and then massive, fields.<ref name="Ellis2012" /> Their contribution, and the work of others on the [[renormalization group|renormalisation group]]{{snd}}including "substantial" theoretical work by Russian physicists [[Ludvig Faddeev]], [[Andrei Slavnov]], [[Efim Fradkin]], and [[Igor Tyutin]]<ref>{{cite web |author=Veltman |first=Martin |date=8 December 1999 |title=From Weak Interactions to Gravitation |url=https://www.nobelprize.org/nobel_prizes/physics/laureates/1999/veltman-lecture.pdf |archive-url=https://web.archive.org/web/20180725112127/https://www.nobelprize.org/nobel_prizes/physics/laureates/1999/veltman-lecture.pdf |archive-date=25 July 2018 |access-date=9 October 2013 |website=The Nobel Prize |page=391}}</ref>{{snd}}was eventually "enormously profound and influential",<ref name="Politzer 2004">{{cite web |last=Politzer |first=David |title=The Dilemma of Attribution |date=8 December 2004 |url=https://www.nobelprize.org/nobel_prizes/physics/laureates/2004/politzer-lecture.html |website=The Nobel Prize |access-date=22 January 2013 |quote=Sidney Coleman published in Science magazine in 1979 a citation search he did documenting that essentially no one paid any attention to Weinberg's Nobel Prize winning paper until the work of 't Hooft (as explicated by Ben Lee). In 1971 interest in Weinberg's paper exploded. I had a parallel personal experience: I took a one-year course on weak interactions from Shelly Glashow in 1970, and he never even mentioned the Weinberg–Salam model or his own contributions. |archive-date=21 March 2013 |archive-url=https://web.archive.org/web/20130321082107/http://www.nobelprize.org/nobel_prizes/physics/laureates/2004/politzer-lecture.html |url-status=live }}</ref> but even with all key elements of the eventual theory published there was still almost no wider interest. For example, [[Sidney Coleman|Coleman]] found in a study that "essentially no-one paid any attention" to Weinberg's paper prior to 1971<ref>{{cite journal |last=Coleman |first=Sidney |author-link=Sidney Coleman |title=The 1979 Nobel Prize in Physics |journal=[[Science (magazine)|Science]] |date=14 December 1979 |volume=206 |issue=4424 |pages=1290–1292 |doi=10.1126/science.206.4424.1290 |pmid=17799637|bibcode = 1979Sci...206.1290C}}</ref> and discussed by [[David Politzer]] in his 2004 Nobel speech.<ref name="Politzer 2004" />{{snd}}now the most cited in particle physics<ref name="PRL_50years">[http://prl.aps.org/50years/milestones#1967]{{Webarchive|url=https://archive.today/20100110134128/http://prl.aps.org/50years/milestones#1967|date=10 January 2010}}. Letters from the Past{{snd}}A PRL Retrospective (50 year celebration, 2008).</ref>{{snd}}and even in 1970 according to Politzer, Glashow's teaching of the weak interaction contained no mention of Weinberg's, Salam's, or Glashow's own work.<ref name="Politzer 2004" /> In practice, Politzer states, almost everyone learned of the theory due to physicist [[Benjamin W. Lee|Benjamin Lee]], who combined the work of Veltman and 't Hooft with insights by others, and popularised the completed theory.<ref name="Politzer 2004" /> In this way, from 1971, interest and acceptance "exploded"<ref name="Politzer 2004" /> and the ideas were quickly absorbed in the mainstream.<ref name="Ellis2012" /><ref name="Politzer 2004" />

The resulting electroweak theory and Standard Model have [[Standard Model#Tests and predictions|accurately predicted]] (among other things) [[weak neutral current]]s, [[W and Z bosons|three bosons]], the [[top quark|top]] and [[charm quark]]s, and with great precision, the mass and other properties of some of these.{{efn|name=predictions}} Many of those involved eventually won Nobel Prizes or other renowned awards. A 1974 paper and comprehensive review in ''[[Reviews of Modern Physics]]'' commented that "while no one doubted the [mathematical] correctness of these arguments, no one quite believed that nature was diabolically clever enough to take advantage of them",<ref>{{harvnb|Bernstein |1974|p=9}}</ref> adding that the theory had so far produced accurate answers that accorded with experiment, but it was unknown whether the theory was fundamentally correct.<ref>{{harvnb|Bernstein |1974 |pp=9, 36 (footnote), 43–44, 47}}</ref> By 1986 and again in the 1990s it became possible to write that understanding and proving the Higgs sector of the Standard Model was "the central problem today in particle physics".<ref name="Proceedings_1986">{{cite book |author1=José Luis Lucio |author2=Arnulfo Zepeda |title=Proceedings of the II Mexican School of Particles and Fields, Cuernavaca-Morelos, 1986 |year=1987 |publisher=World Scientific |isbn=978-9971-5-0434-2 |page=29 |url=https://books.google.com/books?id=jJ-yAAAAIAAJ&q=higgs+%22central+problem+today+in+particle+physics%22 |access-date=5 September 2020 |archive-date=25 January 2022 |archive-url=https://web.archive.org/web/20220125094509/https://books.google.com/books?id=jJ-yAAAAIAAJ&q=higgs+%22central+problem+today+in+particle+physics%22 |url-status=live }}</ref><ref name="Higgs_Hunters_Guide">{{cite book |last1=Gunion |last2=Dawson |last3=Kane |last4=Haber |title=The Higgs Hunter's Guide |edition=1st |year=1990 |page=11 |publisher=Basic Books |url=https://books.google.com/books?id=e8fvAAAAMAAJ&q=central+problem |isbn=978-0-2015-0935-9 |access-date=5 September 2020 |archive-date=25 January 2022 |archive-url=https://web.archive.org/web/20220125094441/https://books.google.com/books?id=e8fvAAAAMAAJ&q=central+problem |url-status=live }} Cited by Peter Higgs in his talk "My Life as a Boson", 2001, ref#25.</ref>

==== Summary and impact of the PRL papers ==== {{wikinews|has=news related to| 2010 Sakurai Prize awarded for 1964 Higgs Boson theory work| Prospective Nobel Prize for Higgs boson work disputed}} The three papers written in 1964 were each recognised as milestone papers during ''[[Physical Review Letters]]''{{'s}} 50th anniversary celebration.<ref name="prl" /> Their six authors were also awarded the 2010 [[Sakurai Prize|J. J. Sakurai Prize for Theoretical Particle Physics]] for this work.<ref name="sakuraiprize">American Physical Society{{snd}}{{cite web |title=J. J. Sakurai Prize for Theoretical Particle Physics |url=http://www.aps.org/units/dpf/awards/sakurai.cfm |url-status=live |archive-url=https://web.archive.org/web/20100212025108/http://www.aps.org/units/dpf/awards/sakurai.cfm |archive-date=12 February 2010 |access-date=2 October 2009}}</ref> (A controversy also arose the same year, because in the event of a Nobel Prize only up to three scientists could be recognised, with six being credited for the papers.<ref>{{cite journal |last=Merali |first=Zeeya |title=Physicists get political over Higgs |url=http://www.nature.com/news/2010/100804/full/news.2010.390.html |access-date=28 December 2011 |journal=[[Nature (journal)|Nature]] |date=4 August 2010 |doi=10.1038/news.2010.390 |archive-date=25 January 2022 |archive-url=https://web.archive.org/web/20220125094451/https://www.nature.com/articles/news.2010.390 |url-status=live |url-access=subscription }}</ref>) Two of the three PRL papers (by Higgs and by GHK) contained equations for the hypothetical [[quantum field theory|field]] that eventually would become known as the Higgs field and its hypothetical [[quantum]], the Higgs boson.<ref name="higgs64" /><ref name="ghk64" /> Higgs's subsequent 1966 paper showed the decay mechanism of the boson; only a massive boson can decay and the decays can prove the mechanism.{{citation needed|date=August 2012}}

In the paper by Higgs the boson is massive, and in a closing sentence Higgs writes that "an essential feature" of the theory "is the prediction of incomplete multiplets of [[scalar boson|scalar]] and [[vector boson]]s".<ref name="higgs64" /> ([[Frank Close]] comments that 1960s gauge theorists were focused on the problem of massless ''vector'' bosons, and the implied existence of a massive ''scalar'' boson was not seen as important; only Higgs directly addressed it.<ref name="frank_close_infinity_puzzle">{{cite book|last=Close|first=Frank|author-link=Frank Close|title=The Infinity Puzzle: Quantum Field Theory and the Hunt for an Orderly Universe|year=2011|publisher=Oxford University Press|location=Oxford|isbn=978-0-19-959350-7}}</ref>{{rp|154, 166, 175}}) In the paper by GHK the boson is massless and decoupled from the massive states.<ref name="ghk64" /> In reviews dated 2009 and 2011, Guralnik states that in the GHK model the boson is massless only in a lowest-order approximation, but it is not subject to any constraint and acquires mass at higher orders, and adds that the GHK paper was the only one to show that there are no massless [[Goldstone boson]]s in the model and to give a complete analysis of the general Higgs mechanism.<ref name="Guralnik 2011" /><ref name="Guralnik 2009">{{Cite journal |author=Guralnik |first=G. S. |year=2009 |title=The History of the Guralnik, Hagen and Kibble development of the Theory of Spontaneous Symmetry Breaking and Gauge Particles |journal=[[International Journal of Modern Physics A]] |volume=24 |issue=14 |pages=2601–2627 |arxiv=0907.3466 |bibcode=2009IJMPA..24.2601G |doi=10.1142/S0217751X09045431 |s2cid=16298371}}</ref> All three reached similar conclusions, despite their very different approaches: Higgs's paper essentially used classical techniques, Englert and Brout's involved calculating vacuum polarisation in perturbation theory around an assumed symmetry-breaking vacuum state, and GHK used operator formalism and conservation laws to explore in depth the ways in which Goldstone's theorem was avoided.<ref name="scholarpedia" /><ref>{{Cite journal |arxiv = 1401.6924|bibcode = 2014MPLA...2950046G|title = Where have all the Goldstone bosons gone?|journal = Modern Physics Letters A|volume = 29|issue = 9|page = 1450046|last1 = Guralnik|first1 = G. S|last2 = Hagen|first2 = C. R|year = 2014|doi = 10.1142/S0217732314500461|s2cid = 119257339}}</ref> Some versions of the theory predicted more than one kind of Higgs fields and bosons, and alternative [[Higgsless model|"Higgsless" models]] were considered until the discovery of the Higgs boson.

=== Experimental search === {{Main|Search for the Higgs boson}} To [[#Production|produce Higgs bosons]], two beams of particles are accelerated to very high energies and allowed to collide within a [[particle detector]]. Occasionally, although rarely, a Higgs boson will be created fleetingly as part of the collision byproducts. Because the Higgs boson [[#Decay|decays]] very quickly, particle detectors cannot detect it directly. Instead the detectors register all the decay products (the ''decay signature'') and from the data the decay process is reconstructed. If the observed decay products match a possible decay process (known as a ''decay channel'') of a Higgs boson, this indicates that a Higgs boson may have been created. In practice, many processes may produce similar decay signatures. Fortunately, the Standard Model precisely predicts the likelihood of each of these, and each known process, occurring. So, if the detector detects more decay signatures consistently matching a Higgs boson than would otherwise be expected if Higgs bosons did not exist, then this would be strong evidence that the Higgs boson exists.

Because Higgs boson production in a particle collision is likely to be very rare (1 in 10 billion at the LHC),{{efn|name="production_rate"| The example is based on the production rate at the LHC operating at 7 TeV. The total cross-section for producing a Higgs boson at the LHC is about 10 [[picobarn]],<ref name=HprodLHC/> while the total cross-section for a proton–proton collision is 110 [[millibarn]].<ref> {{cite web |title=Collisions |series=LHC machine outreach |publisher=[[CERN]] |url=http://lhc-machine-outreach.web.cern.ch/lhc-machine-outreach/collisions.htm |access-date=26 July 2012 |url-status=live |archive-url=https://web.archive.org/web/20200326021534/https://lhc-machine-outreach.web.cern.ch/lhc-machine-outreach/collisions.htm |archive-date=26 March 2020 }} </ref> }} and many other possible collision events can have similar decay signatures, the data of hundreds of trillions of collisions needs to be analysed and must "show the same picture" before a conclusion about the existence of the Higgs boson can be reached. To conclude that a new particle has been found, [[particle physicist]]s require that the [[statistical analysis]] of two independent particle detectors each indicate that there is less than a one-in-a-million chance that the observed decay signatures are due to just background random Standard Model events{{snd}}i.e., that the observed number of events is more than five [[standard deviation]]s (sigma) different from that expected if there was no new particle. More collision data allows better confirmation of the physical properties of any new particle observed, and allows physicists to decide whether it is indeed a Higgs boson as described by the Standard Model or some other hypothetical new particle.

To find the Higgs boson, a powerful [[particle accelerator]] was needed, because Higgs bosons might not be seen in lower-energy experiments. The collider needed to have a high [[Luminosity (scattering theory)|luminosity]] in order to ensure enough collisions were seen for conclusions to be drawn. Finally, advanced computing facilities were needed to process the vast amount of data (25 [[petabyte]]s per year as of 2012) produced by the collisions.<ref name=msnbc-discovery/> For the announcement of 4 July 2012, a new collider known as the [[Large Hadron Collider]] was constructed at [[CERN]] with a planned eventual collision energy of 14 [[TeV]]{{snd}}over seven times any previous collider{{snd}}and over 300 trillion ({{val|3|e=14}}) LHC proton–proton collisions were analysed by the [[LHC Computing Grid]], the world's largest [[computing grid]] (as of 2012), comprising over 170 computing facilities in a [[distributed computing|worldwide network]] across 36 countries.<ref name=msnbc-discovery/><ref>{{cite web |url=http://wlcg.web.cern.ch/ |title=Welcome to the Worldwide LHC Computing Grid |website=WLCG{{snd}} Worldwide LHC Computing Grid |publisher=CERN |access-date=14 November 2012 |quote=[A] global collaboration of more than 170 computing centres in 36 countries ... to store, distribute and analyse the ~25 Petabytes (25 million Gigabytes) of data annually generated by the Large Hadron Collider |archive-date=25 July 2018 |archive-url=https://web.archive.org/web/20180725112849/http://wlcg.web.cern.ch/ |url-status=live }}</ref><ref>{{cite web |url=https://home.cern/about/computing/worldwide-lhc-computing-grid |title=The Worldwide LHC Computing Grid |website=The Worldwide LHC Computing Grid |publisher=CERN |date=November 2017 |quote=It now links thousands of computers and storage systems in over 170 centres across 41 countries. ... The WLCG is the world's largest computing grid |access-date=5 November 2017 |archive-date=7 November 2017 |archive-url=https://web.archive.org/web/20171107014344/https://home.cern/about/computing/worldwide-lhc-computing-grid |url-status=live }}</ref>

==== Search before 4 July 2012 ==== The first extensive search for the Higgs boson was conducted at the [[Large Electron–Positron Collider]] (LEP) at CERN in the 1990s. At the end of its service in 2000, LEP had found no conclusive evidence for the Higgs.{{efn| Just before LEP's shut down, some events that hinted at a Higgs were observed, but it was not judged significant enough to extend its run and delay construction of the LHC. }} This implied that if the Higgs boson were to exist it would have to be heavier than {{val|114.4|u=GeV/c2}}.<ref name="Yao 2006">{{cite journal |author=Yao, W.-M. |display-authors=etal |year=2006 |title=Review of Particle Physics |journal=[[Journal of Physics G]] |volume=33 |issue=1 |pages=1–1232 |arxiv=astro-ph/0601168 |bibcode=2006JPhG...33....1Y|doi=10.1088/0954-3899/33/1/001 |s2cid=117958297 |url=http://pdg.lbl.gov/2006/reviews/higgs_s055.pdf |access-date=25 October 2006 |url-status=live |archive-url=https://web.archive.org/web/20170127020424/http://pdg.lbl.gov/2006/reviews/higgs_s055.pdf |archive-date=27 January 2017}}</ref>

The search continued at [[Fermilab]] in the United States, where the [[Tevatron]]{{snd}}the collider that discovered the [[top quark]] in 1995 – had been upgraded for this purpose. There was no guarantee that the Tevatron would be able to find the Higgs, but it was the only supercollider that was operational since the [[Large Hadron Collider]] (LHC) was still under construction and the planned [[Superconducting Super Collider]] had been cancelled in 1993 and never completed. The Tevatron was only able to exclude further ranges for the Higgs mass, and was shut down on 30 September 2011 because it no longer could keep up with the LHC. The final analysis of the data excluded the possibility of a Higgs boson with a mass between {{val|147|u=GeV/c2}} and {{val|180|u=GeV/c2}}. In addition, there was a small (but not significant) excess of events possibly indicating a Higgs boson with a mass between {{val|115|u=GeV/c2}} and {{val|140|u=GeV/c2}}.<ref>{{cite arXiv |title=Updated combination of CDF and D0 searches for Standard Model Higgs boson production with up to {{val|10.0|u=fb-1}} of data |author1=The CDF Collaboration |author2=((The D0 Collaboration)) |author3=The Tevatron New Physics, Higgs Working Group |eprint=1207.0449 |class=hep-ex |year=2012}}</ref>

The [[Large Hadron Collider]] at [[CERN]] in Switzerland, was designed specifically to be able to either confirm or exclude the existence of the Higgs boson. Built in a 27 km tunnel under the ground near [[Geneva]] originally inhabited by LEP, it was designed to collide two beams of protons, initially at energies of {{val|3.5|u=TeV}} per beam (7 TeV total), or almost 3.6 times that of the Tevatron, and upgradeable to {{nowrap|2 × 7 TeV}} (14 TeV total) in future. Theory suggested if the Higgs boson existed, collisions at these energy levels should be able to reveal it. As one of the [[List of megaprojects#Science projects|most complicated scientific instruments]] ever built, its operational readiness was delayed for 14 months by a [[Magnet quench|magnet quench event]] nine days after its inaugural tests, caused by a faulty electrical connection that damaged over 50 superconducting magnets and contaminated the vacuum system.<ref>{{cite web |date=15 October 2008 |title=Interim Summary Report on the Analysis of the 19 September 2008 Incident at the LHC|url=https://edms.cern.ch/file/973073/1/Report_on_080919_incident_at_LHC__2_.pdf|publisher=CERN|id=EDMS 973073|access-date=28 September 2009|archive-date=20 August 2013|archive-url=https://web.archive.org/web/20130820095728/https://edms.cern.ch/file/973073/1/Report_on_080919_incident_at_LHC__2_.pdf|url-status=live}}</ref><ref>{{cite press release|date=16 October 2008|title=CERN releases analysis of LHC incident|url=http://press.cern/press-releases/2008/10/cern-releases-analysis-lhc-incident|website=Media and Press relations|publisher=CERN|access-date=12 November 2016|archive-date=12 November 2016|archive-url=https://web.archive.org/web/20161112211334/http://press.cern/press-releases/2008/10/cern-releases-analysis-lhc-incident|url-status=live}}</ref><ref name="CERNsummer">{{cite press release |date=5 December 2008 |title=LHC to restart in 2009 |url=http://press.cern/press-releases/2008/12/lhc-restart-2009 |website=Media and Press relations |publisher=CERN|access-date=12 November 2016 |archive-date=12 November 2016 |archive-url=https://web.archive.org/web/20161112211157/http://press.cern/press-releases/2008/12/lhc-restart-2009 |url-status=live}}</ref>

Data collection at the LHC finally commenced in March 2010.<ref>{{cite journal|url=http://cdsweb.cern.ch/journal/CERNBulletin/2010/18/News%20Articles/1262593|title=LHC progress report|journal=CERN Bulletin|issue=18|date=3 May 2010|access-date=7 December 2011|archive-date=26 May 2018|archive-url=https://web.archive.org/web/20180526031452/http://cdsweb.cern.ch/journal/CERNBulletin/2010/18/News+Articles/1262593|url-status=live}}</ref> By December 2011 the two main particle detectors at the LHC, [[ATLAS experiment|ATLAS]] and [[Compact Muon Solenoid|CMS]], had narrowed down the mass range where the Higgs could exist to around {{val|116|–|130|u=GeV/c2}} (ATLAS) and {{val|115|–|127|u=GeV/c2}} (CMS).<ref name="ATLAS-13Dec2011">{{cite web|url=https://atlas.cern/updates/press-statement/atlas-experiment-presents-latest-higgs-search-status|title=ATLAS experiment presents latest Higgs search status|website=ATLAS homepage|publisher=CERN|date=13 December 2011|access-date=13 December 2011|archive-date=23 November 2016|archive-url=https://web.archive.org/web/20161123021514/http://atlas.cern/updates/press-statement/atlas-experiment-presents-latest-higgs-search-status|url-status=live}}</ref><ref name="CMS_December 2011">{{cite web|first=Lucas|last=Taylor|url=http://cms.web.cern.ch/news/cms-search-standard-model-higgs-boson-lhc-data-2010-and-2011|title=CMS search for the Standard Model Higgs Boson in LHC data from 2010 and 2011|website=CMS public website|publisher=CERN|date=13 December 2011|access-date=13 December 2011|archive-date=7 January 2012|archive-url=https://web.archive.org/web/20120107165124/http://cms.web.cern.ch/news/cms-search-standard-model-higgs-boson-lhc-data-2010-and-2011|url-status=live}}</ref> There had also already been a number of promising event excesses that had "evaporated" and proven to be nothing but random fluctuations. However, from around May 2011,<ref name="NYT-20130305"> {{cite news |last=Overbye |first=Dennis |author-link=Dennis Overbye |date=5 March 2013 |title=Chasing The Higgs Boson |url=https://www.nytimes.com/2013/03/05/science/chasing-the-higgs-boson-how-2-teams-of-rivals-at-CERN-searched-for-physics-most-elusive-particle.html |url-status=live |archive-url=https://web.archive.org/web/20130305022631/http://www.nytimes.com/2013/03/05/science/chasing-the-higgs-boson-how-2-teams-of-rivals-at-CERN-searched-for-physics-most-elusive-particle.html |archive-date=5 March 2013 |access-date=5 March 2013 |work=[[The New York Times]]}}</ref> both experiments had seen among their results, the slow emergence of a small yet consistent excess of gamma and 4-lepton decay signatures and several other particle decays, all hinting at a new particle at a mass around {{val|125|u=GeV/c2}}.<ref name="NYT-20130305" /> By around November 2011, the anomalous data at {{val|125|u=GeV/c2}} was becoming "too large to ignore" (although still far from conclusive), and the team leaders at both ATLAS and CMS each privately suspected they might have found the Higgs.<ref name="NYT-20130305" /> On 28 November 2011, at an internal meeting of the two team leaders and the director general of CERN, the latest analyses were discussed outside their teams for the first time, suggesting both ATLAS and CMS might be converging on a possible shared result at {{val|125|u=GeV/c2}}, and initial preparations commenced in case of a successful finding.<ref name="NYT-20130305" /> While this information was not known publicly at the time, the narrowing of the possible Higgs range to around {{val|115|–|130|u=GeV/2}} and the repeated observation of small but consistent event excesses across multiple channels at both ATLAS and CMS in the {{val|124|–|126|u=GeV/c2}} region (described as "tantalising hints" of around 2–3 sigma) were public knowledge with "a lot of interest".<ref name="CERN 13 dec 2011">{{cite press release|date=13 December 2011|title=ATLAS and CMS experiments present Higgs search status|url=http://press.web.cern.ch/press-releases/2011/12/atlas-and-cms-experiments-present-higgs-search-status|publisher=CERN Press Office|quote=the statistical significance is not large enough to say anything conclusive. As of today what we see is consistent either with a background fluctuation or with the presence of the boson. Refined analyses and additional data delivered in 2012 by this magnificent machine will definitely give an answer|access-date=14 September 2012|archive-date=13 December 2012|archive-url=https://web.archive.org/web/20121213143159/http://press.web.cern.ch/press-releases/2011/12/atlas-and-cms-experiments-present-higgs-search-status|url-status=live}}</ref> It was therefore widely anticipated around the end of 2011, that the LHC would provide sufficient data to either exclude or confirm the finding of a Higgs boson by the end of 2012, when their 2012 collision data (with slightly higher 8 TeV collision energy) had been examined.<ref name="CERN 13 dec 2011" /><ref>{{cite web |url=http://lcg-archive.web.cern.ch/lcg-archive/public/|title=Welcome |website=WLCG{{snd}} Worldwide LHC Computing Grid |publisher=CERN |access-date=29 October 2012|archive-url=https://web.archive.org/web/20121110182115/http://lcg-archive.web.cern.ch/lcg-archive/public/|archive-date=10 November 2012}}</ref>

==== Discovery of candidate boson at CERN ==== {| class="wikitable floatright" style="font-size:90%; width:220px;" |- | {{nowrap|[[File:2-photon Higgs decay.svg|frameless]]  [[File:4-lepton Higgs decay.svg|frameless]]}} |- | [[Feynman diagram]]s showing the cleanest channels associated with the low-mass (~{{val|125|u=GeV/c2}}) Higgs boson candidate observed by [[ATLAS experiment|ATLAS]] and [[Compact Muon Solenoid|CMS]] at the [[Large Hadron Collider|LHC]]. The dominant production mechanism at this mass involves two [[gluons]] from each proton fusing to a [[Top quark|Top-quark Loop]], which couples strongly to the Higgs field to produce a Higgs boson.{{ubli | ''Left:'' Diphoton channel: Boson subsequently decays into two gamma ray photons by virtual interaction with a [[W and Z bosons|W boson]] loop or [[top quark]] loop. | ''Right:'' The four-lepton "golden channel": Boson emits two [[W and Z bosons|Z bosons]], which each decay into two [[leptons]] (electrons, muons). }} Experimental analysis of these channels reached a significance of more than five [[standard deviation]]s (sigma) in both experiments.<ref name="cmsdez14"> {{cite journal |author=CMS collaboration |author-link=Compact Muon Solenoid |year=2015 |title=Precise determination of the mass of the Higgs boson and tests of compatibility of its couplings with the standard model predictions using proton collisions at 7 and 8 TeV |arxiv=1412.8662 |bibcode=2015EPJC...75..212K |doi=10.1140/epjc/s10052-015-3351-7 |doi-access=free|pmid=25999783 |pmc=4433454 |volume=75 |issue=5 |page=212 |journal=The European Physical Journal C }}</ref><ref name="atlas4lepton14"> {{cite journal |author=ATLAS collaboration |year=2015 |title=Measurements of Higgs boson production and couplings in the four-lepton channel in pp collisions at center-of-mass energies of 7 and 8 TeV with the ATLAS detector |arxiv=1408.5191 |bibcode=2015PhRvD..91a2006A |doi=10.1103/PhysRevD.91.012006 |volume=91 |issue=1 |article-number=012006 |journal=Physical Review D |s2cid=8672143 |author-link=ATLAS experiment }}</ref><ref name="atlasdiphoton14"> {{cite journal |author=ATLAS collaboration |author-link=ATLAS experiment |year=2014 |title=Measurement of Higgs boson production in the diphoton decay channel in pp collisions at center-of-mass energies of 7 and 8 TeV with the ATLAS detector |arxiv=1408.7084 |bibcode=2014PhRvD..90k2015A |doi=10.1103/PhysRevD.90.112015 |volume=90 |issue=11 |article-number=112015 |journal=Physical Review D |s2cid=8202688 }}</ref> |}

On 22 June 2012 [[CERN]] announced an upcoming seminar covering tentative findings for 2012,<ref>{{cite web|url=http://indico.cern.ch/conferenceDisplay.py?confId=196564|title=Press Conference: Update on the search for the Higgs boson at CERN on 4 July 2012|publisher=Indico.cern.ch|date=22 June 2012|access-date=4 July 2012|archive-date=21 July 2012|archive-url=https://web.archive.org/web/20120721025910/https://indico.cern.ch/conferenceDisplay.py?confId=196564|url-status=live}}</ref><ref>{{cite press release |url=http://press.cern/press-releases/2012/06/cern-give-update-higgs-search-curtain-raiser-ichep-conference |title=CERN to give update on Higgs search as curtain raiser to ICHEP conference |website=Media and Press relations |publisher=CERN |date=22 June 2012 |access-date=12 November 2016 |archive-date=12 November 2016 |archive-url=https://web.archive.org/web/20161112210624/http://press.cern/press-releases/2012/06/cern-give-update-higgs-search-curtain-raiser-ichep-conference |url-status=live }}</ref> and shortly afterwards (from around 1 July 2012 according to an analysis of the spreading rumour in social media<ref>{{cite web |title=Scientists analyse global Twitter gossip around Higgs boson discovery |url=http://phys.org/news/2013-01-scientists-analyse-global-twitter-gossip.html |access-date=6 February 2013 |website=Phys.org |date=23 January 2013 |quote=For the first time scientists have been able to analyse the dynamics of social media on a global scale before, during and after the announcement of a major scientific discovery. |archive-date=29 October 2013 |archive-url=https://web.archive.org/web/20131029224033/http://phys.org/news/2013-01-scientists-analyse-global-twitter-gossip.html |url-status=live }} {{cite journal |last1=De Domenico|first1=M. |title=The Anatomy of a Scientific Gossip |arxiv=1301.2952|bibcode=2013NatSR...3.2980D |doi=10.1038/srep02980 |pmid=24135961 |pmc=3798885 |last2=Lima|first2=A. |last3=Mougel|first3=P. |last4=Musolesi|first4=M. |volume=3 |issue= 2013|page=2980 |journal=Scientific Reports |year=2013 }}</ref>) rumours began to spread in the media that this would include a major announcement, but it was unclear whether this would be a stronger signal or a formal discovery.<ref name="timeslive1">{{cite web|url=http://www.timeslive.co.za/scitech/2012/06/28/higgs-boson-particle-results-could-be-a-quantum-leap|title=Higgs boson particle results could be a quantum leap|publisher=Times LIVE|date=28 June 2012|access-date=4 July 2012|archive-date=4 July 2012|archive-url=https://web.archive.org/web/20120704142852/http://www.timeslive.co.za/scitech/2012/06/28/higgs-boson-particle-results-could-be-a-quantum-leap|url-status=live}}</ref><ref>[http://www.abc.net.au/news/2012-07-04/cern-prepares-to-deliver-higgs-particle-findings/4108622 CERN prepares to deliver Higgs particle findings] {{Webarchive|url=https://web.archive.org/web/20210317211647/https://www.abc.net.au/news/2012-07-04/cern-prepares-to-deliver-higgs-particle-findings/4108622 |date=17 March 2021 }}, Australian Broadcasting Corporation. Retrieved 4 July 2012.</ref> Speculation escalated to a "fevered" pitch when reports emerged that [[Peter Higgs]], who proposed the particle, was to be attending the seminar,<ref>{{cite web |url=http://www.huffingtonpost.co.uk/2012/07/03/god-particle-finally-discovered-peter-higgs_n_1645865.html |title=God Particle Finally Discovered? Higgs Boson News At Cern Will Even Feature Scientist It's Named After |date=3 July 2012 |publisher=Huffingtonpost.co.uk |access-date=19 January 2013 |archive-date=11 March 2013 |archive-url=https://web.archive.org/web/20130311143715/http://www.huffingtonpost.co.uk/2012/07/03/god-particle-finally-discovered-peter-higgs_n_1645865.html |url-status=live }}</ref><ref>{{cite news |author=Our Bureau |url=http://www.telegraphindia.com/1120704/jsp/frontpage/story_15689014.jsp |title=Higgs on way, theories thicken{{snd}} Wait for news on God particle |newspaper=The Telegraph{{snd}} India |date=4 July 2012 |access-date=19 January 2013 |archive-date=7 July 2012 |archive-url=https://web.archive.org/web/20120707031156/http://www.telegraphindia.com/1120704/jsp/frontpage/story_15689014.jsp }}</ref> and that "five leading physicists" had been invited{{snd}}generally believed to signify the five living 1964 authors{{snd}}with Higgs, Englert, Guralnik, Hagen attending and Kibble confirming his invitation (Brout having died in 2011).<ref>{{cite news|last=Thornhill|first=Ted|title=God Particle Finally Discovered? Higgs Boson News At Cern Will Even Feature Scientist It's Named After|url=http://www.huffingtonpost.co.uk/2012/07/03/god-particle-finally-discovered-peter-higgs_n_1645865.html|access-date=23 July 2013|newspaper=Huffington Post|date=3 July 2013|archive-date=11 September 2013|archive-url=https://web.archive.org/web/20130911082325/http://www.huffingtonpost.co.uk/2012/07/03/god-particle-finally-discovered-peter-higgs_n_1645865.html|url-status=live}}</ref>

On 4 July 2012 both of the CERN experiments announced they had independently made the same discovery:<ref name="discovery">{{cite journal |author=Cho |first=Adrian |date=13 July 2012 |title=Higgs Boson Makes Its Debut After Decades-Long Search |journal=Science |volume=337 |issue=6091 |pages=141–143 |bibcode=2012Sci...337..141C |doi=10.1126/science.337.6091.141 |pmid=22798574}}</ref> CMS of a previously unknown boson with mass {{val|125.3|0.6|u=GeV/c2}}<ref name=cms0731 /><ref name=cms1207>{{cite web|url=http://cms.web.cern.ch/news/observation-new-particle-mass-125-gev|title=Observation of a New Particle with a Mass of 125 GeV|first=Lucas|last=Taylor|date=4 July 2012|website=CMS Public Website|publisher=CERN|access-date=4 July 2012|archive-date=5 July 2012|archive-url=https://web.archive.org/web/20120705040217/http://cms.web.cern.ch/news/observation-new-particle-mass-125-gev|url-status=live}}</ref> and ATLAS of a boson with mass {{val|126.0|0.6|u=GeV/c2}}.<ref name=atlas1207>{{cite web|title=Latest Results from ATLAS Higgs Search|url=https://atlas.cern/updates/press-statement/latest-results-atlas-higgs-search|website=ATLAS News|publisher=CERN|date=4 July 2012|access-date=4 July 2012|archive-date=23 November 2016|archive-url=https://web.archive.org/web/20161123021048/http://atlas.cern/updates/press-statement/latest-results-atlas-higgs-search|url-status=live}}</ref><ref name=atlas0731> {{cite journal |author=ATLAS collaboration |author-link=ATLAS experiment |year=2012 |title=Observation of a New Particle in the Search for the Standard Model Higgs Boson with the ATLAS Detector at the LHC |journal=[[Physics Letters B]] |volume=716 |issue=1 |pages=1–29 |arxiv=1207.7214 |bibcode=2012PhLB..716....1A |doi=10.1016/j.physletb.2012.08.020 |s2cid=119169617 }}</ref> Using the combined analysis of two interaction types (known as 'channels'), both experiments independently reached a local significance of 5 sigma{{snd}}implying that the probability of getting at least as strong a result by chance alone is less than one in three million. When additional channels were taken into account, the CMS significance was reduced to 4.9 sigma.<ref name=cms1207 />

The two teams had been working 'blinded' from each other from around late 2011 or early 2012,<ref name="NYT-20130305" /> meaning they did not discuss their results with each other, providing additional certainty that any common finding was genuine validation of a particle.<ref name="msnbc-discovery">{{cite web |url=https://www.nbcnews.com/id/wbna47783507 |title=Hunt for Higgs boson hits key decision point |publisher=NBC News |date=6 December 2012 |access-date=19 January 2013 |archive-date=18 May 2020 |archive-url=https://web.archive.org/web/20200518171258/http://www.nbcnews.com/id/47783507 |url-status=live }}</ref> This level of evidence, confirmed independently by two separate teams and experiments, meets the formal level of proof required to announce a confirmed discovery.

On 31 July 2012, the ATLAS collaboration presented additional data analysis on the "observation of a new particle", including data from a third channel, which improved the significance to 5.9 sigma (1 in 588 million chance of obtaining at least as strong evidence by random background effects alone) and mass {{nowrap|126.0 ± 0.4 (stat) ± 0.4 (sys) GeV/''c''2}},<ref name="atlas0731" /> and CMS improved the significance to 5-sigma and mass {{nowrap|125.3 ± 0.4 (stat) ± 0.5 (sys) GeV/''c''2}}.<ref name=cms0731> {{cite journal |author=CMS collaboration |author-link=Compact Muon Solenoid |year=2012 |title=Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC |journal=[[Physics Letters B]] |volume=716 |issue=1 |pages=30–61 |arxiv=1207.7235 |bibcode=2012PhLB..716...30C |doi=10.1016/j.physletb.2012.08.021 }}</ref>

==== New particle tested as a possible Higgs boson ==== Following the 2012 discovery, it was still unconfirmed whether the {{val|125|u=GeV/c2}} particle was a Higgs boson. On one hand, observations remained consistent with the observed particle being the Standard Model Higgs boson, and the particle decayed into at least some of the predicted channels. Moreover, the production rates and branching ratios for the observed channels broadly matched the predictions by the Standard Model within the experimental uncertainties. However, the experimental uncertainties still left room for alternative explanations, meaning an announcement of the discovery of a Higgs boson would have been premature.<ref name="PDGreview2012" /> To allow more opportunity for data collection, the LHC's proposed 2012 shutdown and 2013–14 upgrade were postponed by seven weeks into 2013.<ref>{{cite journal |title=LHC 2012 proton run extended by seven weeks |url=http://cdsweb.cern.ch/journal/CERNBulletin/2012/30/News%20Articles/1462536?ln=en |first=James |last=Gillies |website=CERN Bulletin |issue=30 |date=23 July 2012 |access-date=29 August 2012 |archive-date=26 May 2018 |archive-url=https://web.archive.org/web/20180526031450/http://cdsweb.cern.ch/journal/CERNBulletin/2012/30/News+Articles/1462536?ln=en |url-status=live }}</ref>

In November 2012, in a conference in Kyoto researchers said evidence gathered since July was falling into line with the basic Standard Model more than its alternatives, with a range of results for several interactions matching that theory's predictions.<ref name="BBC Nov 2012">{{cite news |url=http://www.3news.co.nz/Higgs-boson-behaving-as-expected/tabid/1160/articleID/276802/Default.aspx |work=3 News NZ |title=Higgs boson behaving as expected |date=15 November 2012 |access-date=15 November 2012 |archive-url=https://web.archive.org/web/20140501135844/http://www.3news.co.nz/Higgs-boson-behaving-as-expected/tabid/1160/articleID/276802/Default.aspx |archive-date=1 May 2014 }}</ref> Physicist [[Matt Strassler]] highlighted "considerable" evidence that the new particle is not a [[pseudoscalar]] negative [[Parity (physics)|parity]] particle (consistent with this required finding for a Higgs boson), "evaporation" or lack of increased significance for previous hints of non-Standard Model findings, expected Standard Model interactions with [[W and Z bosons]], absence of "significant new implications" for or against [[supersymmetry]], and in general no significant deviations to date from the results expected of a Standard Model Higgs boson.{{efn|name="strassler nov 2012"|ATLAS and CMS only just co-discovered this particle in July ... We will not know after today whether it is a Higgs at all, whether it is a Standard Model Higgs or not, or whether any particular speculative idea ... is now excluded ... Knowledge about nature does not come easy. We discovered the top quark in 1995, and we are still learning about its properties today ... we will still be learning important things about the Higgs during the coming few decades. We've no choice but to be patient. — M. Strassler (2012)<ref>{{cite web |last=Strassler |first=Matt |date=14 November 2012 |title=Higgs Results at Kyoto |website=Of Particular Significance: Conversations about science with theoretical physicist Matt Strassler |type=personal website |url=http://profmattstrassler.com/2012/11/14/higgs-results-at-kyoto/ |access-date=10 January 2013 |archive-date=8 March 2021 |archive-url=https://web.archive.org/web/20210308075720/https://profmattstrassler.com/2012/11/14/higgs-results-at-kyoto/ |url-status=live }}</ref>}} However some kinds of extensions to the Standard Model would also show very similar results;<ref name="Guardian Nov 2012">{{cite news |last=Sample |first=Ian |title=Higgs particle looks like a bog Standard Model boson, say scientists |url=https://www.theguardian.com/science/2012/nov/14/higgs-standard-model-boson |access-date=15 November 2012 |newspaper=The Guardian |date=14 November 2012 |location=London, UK |archive-date=26 January 2016 |archive-url=https://web.archive.org/web/20160126044115/http://www.theguardian.com/science/2012/nov/14/higgs-standard-model-boson |url-status=live }}</ref> so commentators noted that based on other particles that are still being understood long after their discovery, it may take years to be sure, and decades to fully understand the particle that has been found.<ref name="BBC Nov 2012" />{{efn|name="strassler nov 2012"}}

These findings meant that as of January 2013, scientists were very sure they had found an unknown particle of mass ~ {{val|125|u=GeV/c2}}, and had not been misled by experimental error or a chance result. They were also sure, from initial observations, that the new particle was some kind of boson. The behaviours and properties of the particle, so far as examined since July 2012, also seemed quite close to the behaviours expected of a Higgs boson. Even so, it could still have been a Higgs boson or some other unknown boson, since future tests could show behaviours that do not match a Higgs boson, so as of December 2012 CERN still only stated that the new particle was "consistent with" the Higgs boson,<ref name=Biever-2012-07-Dieter/><ref name="CERN Nov 2012"/> and scientists did not yet positively say it was the Higgs boson.<ref name=cern1207>{{cite press release |website=Media and Press relations |url=http://press.cern/press-releases/2012/07/cern-experiments-observe-particle-consistent-long-sought-higgs-boson |title=CERN experiments observe particle consistent with long-sought Higgs boson |publisher=CERN |date=4 July 2012 |access-date=12 November 2016 |archive-date=21 November 2017 |archive-url=https://web.archive.org/web/20171121031500/http://press.cern/press-releases/2012/07/cern-experiments-observe-particle-consistent-long-sought-higgs-boson |url-status=live }}</ref> Despite this, in late 2012, widespread media reports announced (incorrectly) that a Higgs boson had been confirmed during the year.{{refn| 1=The discovery of the Higgs boson was announced in articles in ''[[Time (magazine)|Time]]'',<ref>{{cite news | url=https://poy.time.com/2012/12/19/the-higgs-boson-particle-of-the-year/ | magazine=Time | title=Person of the year 2012 | date=19 December 2012 | access-date=13 February 2013 | archive-date=12 February 2013 | archive-url=https://web.archive.org/web/20130212232314/http://poy.time.com/2012/12/19/the-higgs-boson-particle-of-the-year/ | url-status=live }}</ref> [[Forbes]],<ref>{{cite web |last1=Knapp |first1=Alex |url=https://www.forbes.com/sites/alexknapp/2012/09/12/higgs-boson-discovery-has-been-confirmed/ |title=Higgs boson discovery has been confirmed |magazine=Forbes |access-date=9 October 2013 |archive-date=25 October 2013 |archive-url=https://web.archive.org/web/20131025001027/http://www.forbes.com/sites/alexknapp/2012/09/12/higgs-boson-discovery-has-been-confirmed/ |url-status=live }}</ref> ''[[Slate (magazine)|Slate]]'',<ref>{{cite web |url=http://www.slate.com/blogs/trending/2012/09/11/higgs_boson_confirmed_cern_discovery_passes_test.html |title=Higgs boson confirmed; CERN discovery passes test |website=Slate.com |date=11 September 2012 |access-date=9 October 2013 |archive-date=9 July 2013 |archive-url=https://web.archive.org/web/20130709123336/http://www.slate.com/blogs/trending/2012/09/11/higgs_boson_confirmed_cern_discovery_passes_test.html |url-status=live }}</ref> ''[[NPR]]'',<ref>{{cite news |url=https://www.npr.org/2013/01/01/168208273/the-year-of-the-higgs-and-other-tiny-advances-in-science |title=The year of the Higgs, and other tiny advances in science |website=NPR.org |publisher=[[National Public Radio]] |date=1 January 2013 |access-date=9 October 2013 |archive-date=5 March 2014 |archive-url=https://web.archive.org/web/20140305192631/http://www.npr.org/2013/01/01/168208273/the-year-of-the-higgs-and-other-tiny-advances-in-science |url-status=live }}</ref> and others.<ref>{{cite news | url=https://www.smh.com.au/world/science/confirmed-the-higgs-boson-does-exist-20120704-21hac.html |newspaper=[[The Sydney Morning Herald]] | title=Confirmed: The Higgs boson does exist | date=4 July 2012 | access-date=21 February 2020 | archive-date=25 January 2022 | archive-url=https://web.archive.org/web/20220125094442/https://www.smh.com.au/world/confirmed-the-higgs-boson-does-exist-20120704-21hac.html | url-status=live }}</ref> }}

In January 2013, CERN director-general [[Rolf-Dieter Heuer]] stated that based on data analysis to date, an answer could be possible 'towards' mid-2013,<ref name="status Jan 2013">{{cite web |author=Heilprin |first=John |date=27 January 2013 |title=CERN chief: Higgs boson quest could wrap up by midyear |url=https://www.nbcnews.com/id/wbna50601148 |url-status=live |archive-url=https://web.archive.org/web/20130221014209/http://www.nbcnews.com/id/50601148/ns/technology_and_science-science/#.USVTVx287-Y |archive-date=21 February 2013 |access-date=20 February 2013 |website=NBCNews.com |quote=Rolf Heuer, director of [CERN], said he is confident that "towards the middle of the year, we will be there." |agency=AP}}{{snd}}Interview by AP, at the World Economic Forum, 26 January 2013.</ref> and the deputy chair of physics at [[Brookhaven National Laboratory]] stated in February 2013 that a "definitive" answer might require "another few years" after the [[Large Hadron Collider#Run 2: second operational run (2015–2018)|collider's 2015 restart]].<ref>{{cite web |last=Boyle |first=Alan |title=Will our universe end in a 'big slurp'? Higgs-like particle suggests it might |url=http://cosmiclog.nbcnews.com/_news/2013/02/18/17006552-will-our-universe-end-in-a-big-slurp-higgs-like-particle-suggests-it-might?lite |access-date=20 February 2013 |website=NBCNews.com |date=16 February 2013 |quote='It's going to take another few years' after the collider is restarted to confirm definitively that the newfound particle is the Higgs boson. |archive-date=21 February 2013 |archive-url=https://web.archive.org/web/20130221030545/http://cosmiclog.nbcnews.com/_news/2013/02/18/17006552-will-our-universe-end-in-a-big-slurp-higgs-like-particle-suggests-it-might?lite |url-status=live }}</ref> In early March 2013, CERN Research Director Sergio Bertolucci stated that confirming spin-0 was the major remaining requirement to determine whether the particle is at least some kind of Higgs boson.<ref>{{cite web |last=Gillies |first=James |title=A question of spin for the new boson |url=http://home.web.cern.ch/about/updates/2013/03/question-spin-new-boson |publisher=[[CERN]] |access-date=7 March 2013 |date=6 March 2013 |archive-date=8 March 2013 |archive-url=https://web.archive.org/web/20130308172228/http://home.web.cern.ch/about/updates/2013/03/question-spin-new-boson |url-status=live }}</ref>

{{anchor|Current status}}

==== Confirmation of existence and status ====

On 14 March 2013 CERN confirmed the following:

<blockquote>CMS and ATLAS have compared a number of options for the spin-parity of this particle, and these all prefer no spin and even parity [two fundamental criteria of a Higgs boson consistent with the Standard Model]. This, coupled with the measured interactions of the new particle with other particles, strongly indicates that it is a Higgs boson.<ref name="CERN March 2013"/></blockquote> This also makes the particle the first elementary [[scalar boson|scalar particle]] to be discovered in nature.<ref name="WSJ 14 March 2013"/>

The following are examples of tests used to confirm that the discovered particle is the Higgs boson:{{efn|name="strassler nov 2012"}}<ref name="when higgs"> {{cite web |author=Falkowski, Adam (writing as 'Jester') |date=27 February 2013 |title=When shall we call it Higgs? |publisher=Résonaances particle physics |type=blog |url=http://resonaances.blogspot.co.uk/2013/02/when-shall-we-call-it-higgs.html |access-date=7 March 2013 |url-status=live |archive-url=https://web.archive.org/web/20170629162456/http://resonaances.blogspot.co.uk/2013/02/when-shall-we-call-it-higgs.html |archive-date=29 June 2017 }} </ref> {| class="wikitable" style="font-size:90%" |- ! Requirement !style="width:48%;"| How tested / explanation ! Status ({{as of|2017|July|lc=y}}) |- | Zero [[Spin (physics)|spin]] || Examining decay patterns. Spin-1 had been ruled out at the time of initial discovery by the observed decay to two {{nobr|photons ({{mvar|γ γ}}),}} leaving spin-0 and spin-2 as remaining candidates. | Spin-0 confirmed.<ref name=CMSspinparity2017/><ref name="CERN March 2013"/><ref name=CMS_spin_parity> {{cite journal | last1 = Chatrchyan | first1 = S. | last2 = Khachatryan | first2 = V. | last3 = Sirunyan | first3 = A.M. | last4 = Tumasyan | first4 = A. | last5 = Adam | first5 = W. | last6 = Aguilo | first6 = E. | last7 = Bergauer | first7 = T. | last8 = Dragicevic | first8 = M. | last9 = Erö | first9 = J. | last10 = Fabjan | first10 = C. | last11 = Friedl | first11 = M. | last12 = Frühwirth | first12 = R. | last13 = Ghete | first13 = V.M. | last14 = Hörmann | first14 = N. | last15 = Hrubec | first15 = J. | last16 = Jeitler | first16 = M. | last17 = Kiesenhofer | first17 = W. | last18 = Knünz | first18 = V. | last19 = Krammer | first19 = M. | last20 = Krätschmer | first20 = I. | last21 = Liko | first21 = D. | last22 = Mikulec | first22 = I. | last23 = Pernicka | first23 = M. | last24 = Rabady | first24 = D. | last25 = Rahbaran | first25 = B. | last26 = Rohringer | first26 = C. | last27 = Rohringer | first27 = H. | last28 = Schöfbeck | first28 = R. | last29 = Strauss | first29 = J. | last30 = Taurok | first30 = A. | display-authors = 6 | collaboration = [[Compact Muon Solenoid|CMS]] Collaboration | date = February 2013 | title = Study of the mass and spin-parity of the Higgs boson candidate via its decays to Z boson pairs | journal = Physical Review Letters | volume = 110 | issue = 8 | article-number = 081803 | doi = 10.1103/PhysRevLett.110.081803 | bibcode=2013PhRvL.110h1803C | arxiv = 1212.6639 | s2cid = 2621524 | pmid = 23473131 }} </ref><ref name=ATLAS_spin_parity> {{cite journal | last1 = Aad | first1 = G. | last2 = Abajyan | first2 = T. | last3 = Abbott | first3 = B. | last4 = Abdallah | first4 = J. | last5 = Abdel Khalek | first5 = S. | last6 = Abdinov | first6 = O. | last7 = Aben | first7 = R. | last8 = Abi | first8 = B. | last9 = Abolins | first9 = M. | last10 = Abouzeid | first10 = O.S. | last11 = Abramowicz | first11 = H. | last12 = Abreu | first12 = H. | last13 = Abulaiti | first13 = Y. | last14 = Acharya | first14 = B.S. | last15 = Adamczyk | first15 = L. | last16 = Adams | first16 = D.L. | last17 = Addy | first17 = T.N. | last18 = Adelman | first18 = J. | last19 = Adomeit | first19 = S. | last20 = Adye | first20 = T. | last21 = Aefsky | first21 = S. | last22 = Aguilar-Saavedra | first22 = J.A. | last23 = Agustoni | first23 = M. | last24 = Ahlen | first24 = S.P. | last25 = Ahmad | first25 = A. | last26 = Ahsan | first26 = M. | last27 = Aielli | first27 = G. | last28 = Åkesson | first28 = T.P.A. | last29 = Akimoto | first29 = G. | last30 = Akimov | first30 = A.V. | display-authors = 6 | collaboration = [[ATLAS experiment|ATLAS]] Collaboration | date = 7 October 2013 | title = Evidence for the spin-0 nature of the Higgs boson using ATLAS data | journal = Phys. Lett. B | volume = 726 | issue = 1–3 | pages = 120–144 | arxiv = 1307.1432 | doi = 10.1016/j.physletb.2013.08.026 | bibcode = 2013PhLB..726..120A | s2cid = 11562016 }}</ref> The spin-2 hypothesis is excluded with a confidence level exceeding 99.9%.<ref name=ATLAS_spin_parity/> |- | Even (Positive) [[parity (physics)|parity]] | Studying the angles at which decay products fly apart. Negative parity was also disfavoured if spin-0 was confirmed.<ref> {{cite journal |last1=Chatrchyan |first1=S. |last2=Khachatryan |first2=V. |collaboration=CMS collaboration |year=2013 |title=Higgs-like particle in a mirror |journal=Physical Review Letters |volume=110 |issue=8 |article-number=081803 |doi=10.1103/PhysRevLett.110.081803 |bibcode=2013PhRvL.110h1803C |pmid=23473131 |arxiv=1212.6639 |s2cid=2621524 }} </ref> | Even parity tentatively confirmed.<ref name="CERN March 2013"/><ref name=CMS_spin_parity/><ref name=ATLAS_spin_parity/> The spin-0 negative parity hypothesis is excluded with a confidence level exceeding 99.9%.<ref name=CMS_spin_parity/><ref name="CMSspinparity2017"/> |- | [[Particle decay|Decay channels]] (outcomes of particle decaying) are as predicted | The Standard Model predicts the decay patterns of a {{val|125|u=GeV/c2}} Higgs boson. Are these all being seen, and at the right rates?

Particularly significant, we should observe decays into pairs of {{nobr|[[photon]]s (γ γ),}} [[W and Z bosons]] (W{{sup|−}} W{{sup|+}} and Z Z), [[bottom quark]]s (b {{overline|b}}), and [[tau lepton]]s (τ{{sup|−}}τ{{sup|+}}), among the possible outcomes. | b {{overline|b}}, γ γ, τ{{sup|−}} τ{{sup|+}}, W{{sup|−}} W{{sup|+}} and Z Z observed. All observed signal strengths are consistent with the Standard Model prediction.<ref> {{cite journal |collaboration = ATLAS & CMS Collaborations |year=2016 |title= Measurements of the Higgs boson production and decay rates and constraints on its couplings from a combined ATLAS and CMS analysis of the LHC pp collision data at {{mvar|√s}} = 7 and 8 TeV |volume = 2016 |issue = 8 |page = 45 |journal=Journal of High Energy Physics |bibcode=2016JHEP...08..045A |s2cid=118523967 |arxiv=1606.02266 |doi=10.1007/JHEP08(2016)045 |last1=Aad |first1=G. |last2=Abbott |first2=B. |last3=Abdallah |first3=J. |last4=Abdinov |first4=O. |last5=Abeloos |first5=B. |last6=Aben |first6=R. |last7=Abouzeid |first7=O. S. |last8=Abraham |first8=N. L. |last9=Abramowicz |first9=H. |last10=Abreu |first10=H. |last11=Abreu |first11=R. |last12=Abulaiti |first12=Y. |last13=Acharya |first13=B. S. |last14=Adamczyk |first14=L. |last15=Adams |first15=D. L. |last16=Adelman |first16=J. |last17=Adomeit |first17=S. |last18=Adye |first18=T. |last19=Affolder |first19=A. A. |last20=Agatonovic-Jovin |first20=T. |last21=Agricola |first21=J. |last22=Aguilar-Saavedra |first22=J. A. |last23=Ahlen |first23=S. P. |last24=Ahmadov |first24=F. |last25=Aielli |first25=G. |last26=Akerstedt |first26=H. |last27=Åkesson |first27=T. P. A. |last28=Akimov |first28=A. V. |last29=Alberghi |first29=G. L. |last30=Albert |first30=J. |display-authors=1 }} </ref><ref name=CERN_EPS2017/> |- | [[Coupling (physics)|Couples to mass]] (i.e., strength of interaction with Standard Model particles proportional to their mass) | Particle physicist Adam Falkowski states that the essential qualities of a Higgs boson are that it is a spin-0 (scalar) particle which ''also'' couples to mass (W and Z bosons); proving spin-0 alone is insufficient.<ref name="when higgs"/> | Couplings to mass strongly evidenced ("At 95% confidence level {{mvar|c}}{{sub|V}} is within 15% of the standard model value {{mvar|c}}{{sub|V}} = 1").<ref name="when higgs"/> |- | Higher energy results remain consistent | After the [[Large Hadron Collider#Full operation|LHC's 2015 restart]] at the higher energy of 13 TeV, searches for multiple Higgs particles (as predicted in some theories) and tests targeting other versions of particle theory continued. These higher energy results must continue to give results consistent with Higgs theories. | Analysis of collisions up to July 2017 do not show deviations from the Standard Model, with experimental precisions better than results at lower energies.<ref name=CERN_EPS2017/> |}

==== Findings since 2013 ====

[[File:HiggsCouplings.png|thumb|upright=1.3|Coupling strength to Higgs boson in (top) and ratio to the standard model prediction (bottom) derived from cross section and branching ratio data. In the ''κ'' framework<ref>{{Cite book |last1=Heinemeyer |first1=S. |url=https://cds.cern.ch/record/1559921 |title=Handbook of LHC Higgs Cross Sections: 3. Higgs Properties: Report of the LHC Higgs Cross Section Working Group |last2=Mariotti |first2=C. |last3=Passarino |first3=G. |last4=Tanaka |first4=R. |last5=Andersen |first5=J. R. |last6=Artoisenet |first6=P. |last7=Bagnaschi |first7=E. A. |last8=Banfi |first8=A. |last9=Becher |first9=T. |date=2013 |isbn=978-92-9083-389-5 |series=CERN Yellow Reports: Monographs |doi=10.5170/cern-2013-004}}</ref> the couplings are<math>\sqrt{{\kappa }_{V}}{m}_{V}/{\rm{vev}}\quad (=\sqrt{{\kappa }_{V}{g}_{V}/2{\rm{vev}}})</math> and <math>{\kappa }_{F}{m}_{V}/{\rm{vev}}</math> for the vector bosons V (=Z,W) and for the fermions F ( = ''t'', ''b'', ''τ'' (''μ'' not confirmed as 2022 but there is evidence)) respectively, where <math>{m}_{V/F}</math> the masses and <math>vev</math> the [[vacuum expectation value]] (<math>{g}_{V}</math> the absolute coupling strength).<ref>{{Cite journal |last=The ATLAS Collaboration |date=4 July 2022 |title=A detailed map of Higgs boson interactions by the ATLAS experiment ten years after the discovery |journal=Nature |language=en |volume=607 |issue=7917 |pages=52–59 |doi=10.1038/s41586-022-04893-w |pmid=35788192 |pmc=9259483 |arxiv=2207.00092 |bibcode=2022Natur.607...52A |issn=1476-4687}}</ref>]] In July 2017, CERN confirmed that all measurements still agree with the predictions of the Standard Model, and called the discovered particle simply "the Higgs boson".<ref name="CERN_EPS2017" /> As of 2019, the [[Large Hadron Collider]] has continued to produce findings that confirm the 2013 understanding of the Higgs field and particle.<ref>{{cite web|url=https://home.cern/news/news/physics/highlights-2019-moriond-conference-electroweak-physics|title=Highlights from the 2019 Moriond conference (electroweak physics)|date=29 March 2019|access-date=24 April 2019|archive-date=21 April 2019|archive-url=https://web.archive.org/web/20190421224637/https://home.cern/news/news/physics/highlights-2019-moriond-conference-electroweak-physics|url-status=live}}</ref><ref>{{cite web|url=https://atlas.cern/updates/physics-briefing/adding-more-pieces-higgs-boson-puzzle|title=All together now: adding more pieces to the Higgs boson puzzle|publisher=ATLAS collaboration|date=18 March 2019|access-date=24 April 2019|archive-date=16 April 2019|archive-url=https://web.archive.org/web/20190416210515/https://atlas.cern/updates/physics-briefing/adding-more-pieces-higgs-boson-puzzle|url-status=live}}</ref>

The LHC's experimental work since restarting in 2015 has included probing the Higgs field and boson to a greater level of detail, and confirming whether less common predictions were correct. In particular, exploration since 2015 has provided strong evidence of the predicted direct decay into [[fermion]]s such as pairs of [[bottom quark]]s (3.6 ''σ''){{snd}}described as an "important milestone" in understanding its short lifetime and other rare decays{{snd}}and also to confirm decay into pairs of [[tau lepton]]s (5.9 ''σ''). This was described by CERN as being "of paramount importance to establishing the coupling of the Higgs boson to leptons and represents an important step towards measuring its couplings to third generation fermions, the very heavy copies of the electrons and quarks, whose role in nature is a profound mystery".<ref name="CERN_EPS2017" /> Published results as of 19 March 2018 at 13 TeV for ATLAS and CMS had their measurements of the Higgs mass at {{val|124.98|0.28|u=GeV/c2}} and {{val|125.26|0.21|u=GeV/c2}} respectively.

In July 2018, the ATLAS and CMS experiments reported observing the Higgs boson decay into a pair of bottom quarks, which makes up approximately 60% of all of its decays.<ref>{{cite press release |title=Long-sought decay of Higgs boson observed |date=28 August 2018 |url=https://home.cern/news/press-release/physics/long-sought-decay-higgs-boson-observed |website=Media and Press relations |publisher=CERN |access-date=30 August 2018 |archive-date=22 November 2018 |archive-url=https://web.archive.org/web/20181122092122/https://home.cern/news/press-release/physics/long-sought-decay-higgs-boson-observed |url-status=live }}</ref><ref name="ATLAS-20180828">{{cite press release |author=Atlas Collaboration |title=ATLAS observes elusive Higgs boson decay to a pair of bottom quarks |url=https://atlas.cern/updates/press-statement/observation-higgs-boson-decay-pair-bottom-quarks |date=28 August 2018 |website=Atlas |publisher=CERN |access-date=28 August 2018 |archive-date=28 August 2018 |archive-url=https://web.archive.org/web/20180828094617/http://atlas.cern/updates/press-statement/observation-higgs-boson-decay-pair-bottom-quarks |url-status=live }}</ref><ref>{{cite web |author=CMS Collaboration |date=August 2018 |url=http://cms.cern/higgs-observed-decaying-b-quarks |title=Observation of Higgs boson decay to bottom quarks |website=CMS |access-date=30 August 2018 |archive-date=30 August 2018 |archive-url=https://web.archive.org/web/20180830005005/http://cms.cern/higgs-observed-decaying-b-quarks |url-status=live }} {{cite journal |author=CMS Collaboration |date=24 August 2018 |url=https://cds.cern.ch/record/2636067 |title=Observation of Higgs boson decay to bottom quarks |journal=Physical Review Letters |volume=121 |issue=12 |article-number=121801 |publisher=CERN |doi=10.1103/PhysRevLett.121.121801 |pmid=30296133 |bibcode=2018PhRvL.121l1801S |access-date=30 August 2018 |archive-date=25 January 2022 |archive-url=https://web.archive.org/web/20220125094452/https://cds.cern.ch/record/2636067 |url-status=live |arxiv=1808.08242 |hdl=11384/75886 }} {{Cite journal |author=CMS Collaboration |date=24 August 2018 |title=Observation of Higgs boson decay to bottom quarks |journal= Physical Review Letters|volume=121 |issue=12 |article-number=121801 |arxiv=1808.08242 |doi=10.1103/PhysRevLett.121.121801 |pmid=30296133 |bibcode=2018PhRvL.121l1801S |s2cid=118901756 }}</ref>

== Theoretical issues == {{Main|Higgs mechanism}}

=== Theoretical need for the Higgs === [[File:Spontaneous symmetry breaking (explanatory diagram).png|thumb|upright=1.25|"[[Spontaneous symmetry breaking|Symmetry breaking]] illustrated":{{snd}}At high energy levels ''(left)'' the ball settles in the centre, and the result is symmetrical. At lower energy levels ''(right)'', the overall "rules" remain symmetrical, but the "sombrero potential" comes into effect: [[local property|"local" symmetry]] inevitably becomes broken since eventually the ball must at random roll one way or another.]] [[Gauge invariance]] is an important property of modern particle theories such as the [[Standard Model]], partly due to its success in other areas of fundamental physics such as [[electromagnetism]] and the [[strong interaction]] ([[quantum chromodynamics]]). However, before [[Sheldon Glashow]] extended the [[electroweak unification]] models in 1961, there were great difficulties in developing gauge theories for the [[weak nuclear force]] or a possible unified [[electroweak interaction]]. [[Fermion]]s with a mass term would violate gauge symmetry and therefore cannot be gauge invariant. (This can be seen by examining the [[Lagrangian (field theory)|Dirac Lagrangian]] for a fermion in terms of left and right handed components; we find none of the spin-half particles could ever flip [[helicity (particle physics)|helicity]] as required for mass, so they must be massless.{{efn| In the Standard Model, the mass term arising from the Dirac Lagrangian for any fermion <math>\psi</math> is <math>-m\bar{\psi}\psi</math>. This is ''not'' invariant under the electroweak symmetry, as can be seen by writing <math>\psi</math> in terms of left and right handed components: : <math>-m\bar{\psi}\psi \,=\, -m\left(\bar{\psi}_L\psi_R + \bar{\psi}_R\psi_L\right)</math> i.e., contributions from <math>\bar{\psi}_L\psi_L</math> and <math>\bar{\psi}_R\psi_R</math> terms do not appear. We see that the mass-generating interaction is achieved by constant flipping of particle [[chirality]]. Since the spin-half particles have no right/left helicity pair with the same [[SU(2)]] and [[SU(3)]] representation and the same weak hypercharge, then assuming these gauge charges are conserved in the vacuum, none of the spin-half particles could ever swap helicity. Therefore, in the absence of some other cause, all fermions must be massless. }}) [[W and Z bosons]] are observed to have mass, but a boson mass term contains terms which clearly depend on the choice of gauge, and therefore these masses too cannot be gauge invariant. Therefore, it seems that ''none'' of the standard model fermions ''or'' bosons could "begin" with mass as an inbuilt property except by abandoning gauge invariance. If gauge invariance were to be retained, then these particles had to be acquiring their mass by some other mechanism or interaction.

Additionally, solutions based on spontaneous symmetry breaking appeared to fail, seemingly an inevitable result of [[Goldstone's theorem]]. Because there is no potential energy cost to moving around the complex plane's "circular valley" responsible for spontaneous symmetry breaking, the resulting quantum excitation is pure kinetic energy, and therefore a massless boson ("Goldstone boson"), which in turn implies a new long range force. But no new long range forces or massless particles were detected either. So whatever was giving these particles their mass had to not "break" gauge invariance as the basis for other parts of the theories where it worked well, ''and'' had to not require or predict unexpected massless particles or long-range forces which did not actually seem to exist in nature.

A solution to all of these overlapping problems came from the discovery of a previously unnoticed borderline case hidden in the mathematics of Goldstone's theorem,{{efn|name=GoldstoneNote| [[Goldstone's theorem]] only applies to gauges having [[Lorentz covariance|manifest Lorentz covariance]], a condition that took time to become questioned. But the process of [[quantization (physics)|quantisation]] requires a [[gauge fixing|gauge to be fixed]] and at this point it becomes possible to choose a gauge such as the 'radiation' gauge which is not invariant over time, so that these problems can be avoided. According to {{harvp|Bernstein |1974|p=8}}: {{blockquote|the "radiation gauge" condition {{nowrap|∇⋅A({{mvar|x}}) {{=}} 0}} is clearly not covariant, which means that if we wish to maintain transversality of the photon in all [[Lorentz frame]]s, the [[photon field]] Aμ({{mvar|x}}) cannot transform like a [[four-vector]]. This is no catastrophe, since the photon ''field'' is not an [[observable]], and one can readily show that the S-matrix elements, which ''are'' observable have covariant structures. ... in gauge theories one might arrange things so that one had a symmetry breakdown because of the noninvariance of the vacuum; but, because the Goldstone ''et al.'' proof breaks down, the zero mass Goldstone mesons need not appear. [''emphasis in original'']}} {{harvp|Bernstein|1974}} contains an accessible and comprehensive background and review of this area, see [[#External links|external links]]. }} that under certain conditions it ''might'' theoretically be possible for a symmetry to be broken ''without'' disrupting gauge invariance and ''without'' any new massless particles or forces, and having "sensible" ([[renormalization|renormalisable]]) results mathematically. This became known as the [[Higgs mechanism]].

[[File:Elementary particle interactions.svg|upright=1.25|thumb|Summary of interactions between certain [[elementary particle|particles]] described by the [[Standard Model]]]] The Standard Model hypothesises a [[Quantum field theory|field]] which is responsible for this effect, called the Higgs field (symbol: <math>\phi</math>), which has the unusual property of a non-zero amplitude in its [[ground state]]; i.e., a non-zero [[vacuum expectation value]]. It can have this effect because of its unusual "sombrero" shaped potential whose lowest "point" is not at its "centre". In simple terms, unlike all other known fields, the Higgs field requires ''less'' energy to have a non-zero value than a zero value, so it ends up having a non-zero value ''everywhere''. Below a certain extremely high energy level the existence of this non-zero vacuum expectation [[symmetry breaking|spontaneously breaks]] electroweak [[Introduction to gauge theory|gauge symmetry]] which in turn gives rise to the Higgs mechanism and triggers the acquisition of mass by those particles interacting with the field. This effect occurs because [[scalar field]] components of the Higgs field are "absorbed" by the massive bosons as [[degrees of freedom (physics and chemistry)|degrees of freedom]], and couple to the fermions via [[Yukawa coupling]], thereby producing the expected mass terms. When symmetry breaks under these conditions, the [[Goldstone boson]]s that arise ''interact'' with the Higgs field (and with other particles capable of interacting with the Higgs field) instead of becoming new massless particles. The intractable problems of both underlying theories "neutralise" each other, and the residual outcome is that elementary particles acquire a consistent mass based on how strongly they interact with the Higgs field. It is the simplest known process capable of giving mass to the [[gauge boson]]s while remaining compatible with [[gauge theories]].<ref>{{harvnb|Peskin|Schroeder|1995|pp=717–719, 787–791}}</ref> Its [[quantum]] would be a [[scalar boson]], known as the Higgs boson.<ref>{{harvnb|Peskin|Schroeder|1995|pp=715–716 }}</ref>

=== Simple explanation of the theory, from its origins in superconductivity === The proposed Higgs mechanism arose as a result of theories proposed to explain observations in [[superconductivity]]. A superconductor does not allow penetration by external magnetic fields (the [[Meissner effect]]). This strange observation implies that somehow, the electromagnetic field becomes short ranged during this phenomenon. Successful theories arose to explain this during the 1950s, first for fermions ([[Ginzburg–Landau theory]], 1950), and then for bosons ([[BCS theory]], 1957).

In these theories, superconductivity is interpreted as arising from a [[Bose–Einstein condensate|charged condensate]] field. Initially, the condensate value does not have any preferred direction, implying it is scalar, but its [[Phase (waves)|phase]] is capable of defining a gauge, in gauge based field theories. To do this, the field must be charged. A charged scalar field must also be complex (or described another way, it contains at least two components, and a symmetry capable of rotating each into the other(s)). In naïve gauge theory, a gauge transformation of a condensate usually rotates the phase. But in these circumstances, it instead fixes a preferred choice of phase. However, it turns out that fixing the choice of gauge so that the condensate has the same phase everywhere also causes the electromagnetic field to gain an extra term. This extra term causes the electromagnetic field to become short range.

Once attention was drawn to this theory within particle physics, the parallels were clear. A change of the usually long range electromagnetic field to become short ranged, within a gauge invariant theory, was exactly the needed effect sought for the weak force bosons (because a long range force has massless gauge bosons, and a short ranged force implies massive gauge bosons, suggesting that a result of this interaction is that the field's gauge bosons acquired mass, or a similar and equivalent effect). The features of a field required to do this were also quite well defined – it would have to be a charged scalar field, with at least two components, and complex in order to support a symmetry able to rotate these into each other.{{efn| [[Goldstone's theorem]] also plays a role in such theories. The connection is technically, when a condensate breaks a symmetry, then the state reached by acting with a symmetry generator on the condensate has the same energy as before. This means that some kinds of oscillation will not involve change of energy. Oscillations with unchanged energy imply that excitations (particles) associated with the oscillation are massless. Therefore the outcome is that new massless particles should exist, known as [[Goldstone boson]]s. Because zero mass gauge bosons always mediate long range interactions, a new long range force should exist as well. }}

=== Alternative models === {{Main|Alternatives to the Standard Model Higgs}}

The Minimal Standard Model as described above is the simplest known model for the Higgs mechanism with just one Higgs field. However, an extended Higgs sector with additional Higgs particle doublets or triplets is also possible, and many extensions of the Standard Model have this feature. The non-minimal Higgs sector favoured by theory are the [[Two-Higgs-Doublet Model|two-Higgs-doublet models]] (2HDM), which predict the existence of a [[quintet]] of scalar particles: two [[CP violation|CP-even]] neutral Higgs bosons h0 and H0, a CP-odd neutral Higgs boson A0, and two charged Higgs particles H±. [[Supersymmetry]] ("SUSY") also predicts relations between the Higgs-boson masses and the masses of the gauge bosons, and could accommodate a {{val|125|u=GeV/c2}} neutral Higgs boson.

The key method to distinguish between these different models involves study of the particles' interactions ("coupling") and exact decay processes ("branching ratios"), which can be measured and tested experimentally in particle collisions. In the Type-I 2HDM model one Higgs doublet couples to up and down quarks, while the second doublet does not couple to quarks. This model has two interesting limits, in which the lightest Higgs couples to just fermions ("gauge-[[-phobia|phobic]]") or just gauge bosons ("fermiophobic"), but not both. In the Type-II 2HDM model, one Higgs doublet only couples to up-type quarks, the other only couples to down-type quarks.<ref> {{cite journal |last1=Branco |first1=G. C. |last2=Ferreira |first2=P. M. |last3=Lavoura |first3=L. |last4=Rebelo |first4=M. N. |last5=Sher |first5=Marc |last6=Silva |first6=João P. |date=July 2012 |title=Theory and phenomenology of two-Higgs-doublet models |journal=Physics Reports |volume=516 |issue=1 |pages=1–102 |arxiv=1106.0034 |bibcode=2012PhR...516....1B |doi=10.1016/j.physrep.2012.02.002 |s2cid=119214990}}</ref> The heavily researched [[Minimal Supersymmetric Standard Model]] (MSSM) includes a Type-II 2HDM Higgs sector, so it could be disproven by evidence of a Type-I 2HDM Higgs.{{citation needed|date=July 2012}}

In other models the Higgs scalar is a composite particle. For example, in [[Technicolor (physics)|technicolour]] the role of the Higgs field is played by strongly bound pairs of fermions called [[techniquark]]s. Other models feature pairs of [[top quark]]s (see [[top quark condensate]]). In yet other models, there is [[Higgsless model|no Higgs field at all]] and the electroweak symmetry is broken using extra dimensions.<ref>{{Cite journal |first1=C. |last1=Csaki |first2=C. |last2=Grojean |first3=L. |last3=Pilo |first4=J. |last4=Terning |year=2004|title=Towards a realistic model of Higgsless electroweak symmetry breaking |journal=[[Physical Review Letters]] |volume=92 |issue=10 |article-number=101802 |doi=10.1103/PhysRevLett.92.101802 |pmid=15089195 |arxiv=hep-ph/0308038 |bibcode=2004PhRvL..92j1802C |s2cid=6521798}}</ref><ref>{{Cite journal |first1=C. |last1=Csaki |first2=C. |last2=Grojean |first3=L. |last3=Pilo |first4=J. |last4=Terning |year=2004 |title=Gauge theories on an interval: Unitarity without a Higgs |journal=[[Physical Review D]] |volume=69 |issue=5 |article-number=055006 |doi=10.1103/PhysRevD.69.055006 |last5=Terning |first5=John |arxiv=hep-ph/0305237|bibcode = 2004PhRvD..69e5006C |s2cid=119094852}}</ref>

=== Further theoretical issues and hierarchy problem === {{Main|Hierarchy problem|Hierarchy problem#Higgs mass}} [[File:One-loop-diagram.svg|thumb|A one-loop [[Feynman diagram]] of the first-order correction to the Higgs mass. In the Standard Model the effects of these corrections are potentially enormous, giving rise to the so-called [[hierarchy problem]].]] The Standard Model leaves the mass of the Higgs boson as a [[parameter]] to be measured, rather than a value to be calculated. This is seen as theoretically unsatisfactory, particularly as quantum corrections (related to interactions with [[virtual particle]]s) should apparently cause the Higgs particle to have a mass immensely higher than that observed, but at the same time the Standard Model requires a mass [[order of magnitude|of the order of]] {{val|100|to|1000|u=GeV/c2}} to ensure [[unitarity]] (in this case, to unitarise longitudinal vector boson scattering).<ref name="Hierarchy problem Quantum Diaries">{{cite web|title=The Hierarchy Problem: why the Higgs has a snowball's chance in hell|url=http://www.quantumdiaries.org/2012/07/01/the-hierarchy-problem-why-the-higgs-has-a-snowballs-chance-in-hell/|publisher=Quantum Diaries|access-date=19 March 2013|date=1 July 2012|archive-date=29 March 2013|archive-url=https://web.archive.org/web/20130329014941/http://www.quantumdiaries.org/2012/07/01/the-hierarchy-problem-why-the-higgs-has-a-snowballs-chance-in-hell/|url-status=live}}</ref> Reconciling these points appears to require explaining why there is an almost-perfect cancellation resulting in the visible mass of ~ {{val|125|u=GeV/c2}}, and it is not clear how to do this. Because the weak force is about 1032 times stronger than gravity, and (linked to this) the Higgs boson's mass is so much less than the [[Planck mass]] or the [[grand unification energy]], it appears that either there is some underlying connection or reason for these observations which is unknown and not described by the Standard Model, or some unexplained and extremely precise [[Fine-tuning (physics)|fine-tuning]] of parameters{{snd}}however at present neither of these explanations is proven. This is known as a [[hierarchy problem]].<ref>{{cite web |url=http://profmattstrassler.com/articles-and-posts/particle-physics-basics/the-hierarchy-problem/ |title=The Hierarchy Problem {{pipe}} Of Particular Significance |date=16 August 2011 |publisher=Profmattstrassler.com |access-date=9 October 2013 |archive-date=7 March 2013 |archive-url=https://web.archive.org/web/20130307151957/http://profmattstrassler.com/articles-and-posts/particle-physics-basics/the-hierarchy-problem/ |url-status=live }}</ref> More broadly, the hierarchy problem amounts to the worry that [[physics beyond the standard model|a future theory of fundamental particles and interactions]] should not have excessive fine-tunings or unduly delicate cancellations, and should allow masses of particles such as the Higgs boson to be calculable. The problem is in some ways unique to spin-0 particles (such as the Higgs boson), which can give rise to issues related to quantum corrections that do not affect particles with spin.<ref name="Hierarchy problem Quantum Diaries" /> A [[Hierarchy problem#Theoretical solutions|number of solutions have been proposed]], including [[supersymmetry]], conformal solutions and solutions via extra dimensions such as [[braneworld]] models.

There are also issues of [[quantum triviality]], which suggests that it may not be possible to create a consistent quantum field theory involving elementary scalar particles. This can also lead to a predictable Higgs mass in [[Physics applications of asymptotically safe gravity#Mass_of_the_Higgs_boson|asymptotic safety]] scenarios.<ref>{{cite journal|last=Shaposhnikov|first=Mikhail|author2=Wetterich, Christof|title=Asymptotic safety of gravity and the Higgs boson mass|journal=Physics Letters B|year=2010|volume=683|issue=2–3|pages=196–200|doi=10.1016/j.physletb.2009.12.022|arxiv=0912.0208|bibcode = 2010PhLB..683..196S |s2cid=13820581}}</ref>

== Properties ==

=== Properties of the Higgs field === In the Standard Model, the Higgs field is a scalar [[tachyonic field|tachyonic]] field{{snd}}''scalar'' meaning it does not transform under [[Lorentz transformation]]s, and ''tachyonic'' meaning the field (but '''not''' the particle) has [[imaginary mass]], and in certain configurations must undergo [[symmetry breaking]]. It consists of four components: Two neutral ones and two charged component [[field (physics)|fields]]. Both of the charged components and one of the neutral fields are [[Goldstone boson]]s, which act as the longitudinal third-polarisation components of the massive [[W and Z bosons|W+, W−, and Z bosons]]. The quantum of the remaining neutral component corresponds to (and is theoretically realised as) the massive Higgs boson.<ref name=Gunion1>{{cite book |last=Gunion |first=John |title=The Higgs Hunter's Guide |publisher=Westview Press |edition=illustrated, reprint |year=2000 |pages=1–3 |isbn=978-0-7382-0305-8}}</ref> This component can interact with [[fermions]] via [[Yukawa coupling]] to give them mass as well.

Mathematically, the Higgs field has imaginary mass and is therefore a ''tachyonic'' field.{{efn| People initially thought of tachyons as particles travelling faster than the speed of light ... But we now know that a ''tachyon'' indicates an instability in a theory that contains it. Regrettably for science fiction fans, tachyons are not real physical particles that appear in nature.<ref name=Randall>{{cite book |first=Lisa |last=Randall |date=19 September 2006 |title=Warped Passages: Unraveling the mysteries of the universe's hidden dimensions |publisher=Ecco |isbn=978-0-06-053109-6 |page=286}}</ref> }} While [[tachyon]]s ([[particle]]s that move [[faster-than-light|faster than light]]) are a purely hypothetical concept, ''fields'' with imaginary mass have come to play an important role in modern physics.<ref name="Sen">{{cite journal |title=Rolling tachyon |last=Sen |first=Ashoke |journal=J. High Energy Phys. |date=May 2002 |volume=2002 |issue=204 |page=48 |doi=10.1088/1126-6708/2002/04/048 |arxiv=hep-th/0203211 |bibcode=2002JHEP...04..048S|s2cid=12023565 }}</ref><ref name=Kutasov>{{cite journal |author1=Kutasov, David |author2=Marino, Marcos |author3=Moore, Gregory W. |name-list-style=amp |title=Some exact results on tachyon condensation in string field theory |journal=JHEP |volume=2000 |issue=10 |page=045 |year=2000 |doi=10.1088/1126-6708/2000/10/045 |arxiv=hep-th/0009148 |bibcode=2000JHEP...10..045K|s2cid=15664546 }}</ref> Under no circumstances do any excitations ever propagate faster than light in such theories{{snd}}the presence or absence of a tachyonic mass has no effect whatsoever on the maximum velocity of signals (there is no violation of [[causality]]).<ref name="susskind">{{cite journal |volume=182 |journal=Phys. Rev. |last1=Aharonov |first1=Y. |last2=Komar |first2=A. |last3=Susskind |first3=L. |title=Superluminal Behavior, Causality, and Instability |year=1969 |doi=10.1103/PhysRev.182.1400 |issue=5 |pages=1400–1403 |bibcode=1969PhRv..182.1400A}}</ref> Instead of faster-than-light particles, the imaginary mass creates an instability: Any configuration in which one or more field excitations are tachyonic must spontaneously decay, and the resulting configuration contains no physical tachyons. This process is known as [[tachyon condensation]], and is now believed to be the explanation for how the Higgs mechanism itself arises in nature, and therefore the reason behind electroweak symmetry breaking.

Although the notion of imaginary mass might seem troubling, it is only the field, and not the mass itself, that is quantised. Therefore, the [[field operator]]s at [[Minkowski space|spacelike]] separated points still [[Canonical commutation relation|commute (or anticommute)]], and information and particles still do not propagate faster than light.<ref name="feinberg67">{{cite journal |first=Gerald |last=Feinberg |author-link=Gerald Feinberg |title=Possibility of faster-than-light particles |journal=Physical Review |volume=159 |year=1967 |pages=1089–1105 |doi=10.1103/PhysRev.159.1089 |bibcode=1967PhRv..159.1089F |issue=5}}</ref> Tachyon condensation drives a physical system that has reached a local limit{{snd}}and might naively be expected to produce physical tachyons{{snd}}to an alternate stable state where no physical tachyons exist. Once a tachyonic field such as the Higgs field reaches the minimum of the potential, its quanta are not tachyons any more but rather are ordinary particles such as the Higgs boson.<ref>{{harvnb|Peskin|Schroeder|1995}}</ref>

=== Properties of the Higgs boson === {{Update|section|date=July 2018|reason=With the Higgs boson now empirically confirmed, the paragraphs on the mass should be rephrased to make it clear that they are about what could be predicted before that observation}} Since the Higgs field is [[scalar field|scalar]], the Higgs boson has no [[Spin (physics)|spin]]. The Higgs boson is also its own [[antiparticle]], is [[CP-symmetry|CP-even]], and has zero [[Electric charge|electric]] and [[color charge|colour charge]].<ref name="npr-interview">{{cite news |last=Flatow |first=Ira |date=6 July 2012 |title=At long last, the Higgs particle ... maybe |website=[[NPR]] |url=https://www.npr.org/2012/07/06/156380366/at-long-last-the-higgs-particle-maybe |access-date=10 July 2012 |url-status=live |archive-date=10 July 2012|archive-url=https://web.archive.org/web/20120710010554/http://www.npr.org/2012/07/06/156380366/at-long-last-the-higgs-particle-maybe}}</ref>

The Standard Model does not predict the mass of the Higgs boson.<ref name="atlas-higgs-diagrams">{{cite press release |title=Explanatory figures for the Higgs boson exclusion plots |year=2011 |website=ATLAS News |publisher=CERN |url=http://atlasexperiment.org/news/2011/simplified-plots.html |access-date=6 July 2012 |url-status=live |archive-url=https://web.archive.org/web/20170916094727/http://atlasexperiment.org/news/2011/simplified-plots.html |archive-date=16 September 2017}}</ref> If that mass is between {{val|115|and|180|u=GeV/c2}} (consistent with empirical observations of {{val|125|u=GeV/c2}}), then the Standard Model can be valid at energy scales all the way up to the [[Planck scale]] ({{val|e=19|u=GeV/c2}}).<ref> {{cite report |last1 = Carena |first1 = M. |last2 = Grojean |first2 = C. |last3 = Kado |first3 = M. |last4 = Sharma |first4 = V. |year = 2013 |title = Status of Higgs boson physics |department = [[Lawrence Berkeley Laboratory]] |publisher = [[University of California]] |place = Berkeley, CA |page = 192 |url = http://pdg.lbl.gov/2013/reviews/rpp2013-rev-higgs-boson.pdf |access-date = 5 November 2017 |url-status = live |archive-url = https://web.archive.org/web/20171210003618/http://pdg.lbl.gov/2013/reviews/rpp2013-rev-higgs-boson.pdf |archive-date = 10 December 2017 }} </ref> It should be the only particle in the Standard Model that remains massive even at high energies. Many theorists expect new [[physics beyond the Standard Model]] to emerge at the TeV-scale, based on unsatisfactory properties of the Standard Model.<ref> {{cite conference |last=Lykken |first=Joseph D. |date=27 June 2009 |title=Beyond the Standard Model |book-title=Proceedings of the 2009 European School of High-Energy Physics |place=Bautzen, Germany |arxiv=1005.1676 |bibcode=2010arXiv1005.1676L }} </ref> The highest possible mass scale allowed for the Higgs boson (or some other electroweak symmetry breaking mechanism) is 1.4 TeV; beyond this point, the Standard Model becomes inconsistent without such a mechanism, because [[Unitarity (physics)|unitarity]] is violated in certain scattering processes.<ref> {{cite book |first = Tilman |last=Plehn |year = 2012 |title = Lectures on LHC Physics |series= Lecture Notes in Physics |volume= 844 |at = §1.2.2 |publisher= Springer |isbn = 978-3-642-24039-3 |arxiv = 0910.4182 |bibcode= 2012LNP...844.....P |doi = 10.1007/978-3-642-24040-9 |s2cid=118019449 }} </ref>

It is also possible, although experimentally difficult, to estimate the mass of the Higgs boson indirectly: In the Standard Model, the Higgs boson has a number of indirect effects; most notably, Higgs loops result in tiny corrections to masses of the W and Z bosons. Precision measurements of electroweak parameters, such as the [[Fermi's interaction|Fermi constant]] and masses of the W and Z bosons, can be used to calculate constraints on the mass of the Higgs. As of July 2011, the precision electroweak measurements tell us that the mass of the Higgs boson is likely to be less than about {{val|161|u=GeV/c2}} at 95% [[confidence level]].{{efn| This upper limit would increase to {{val|185|u=GeV/c2}} if the lower bound of {{val|114.4|u=GeV/c2}} from the LEP-2 direct search is allowed for.<ref name=EWWG> {{cite web |title=LEP Electroweak Working Group |publisher=[[CERN]] |url=http://lepewwg.web.cern.ch/LEPEWWG/ |access-date=4 April 2006 |url-status=live |archive-url=https://web.archive.org/web/20080403130809/http://lepewwg.web.cern.ch/LEPEWWG/ |archive-date=3 April 2008 }} </ref> }} These indirect constraints rely on the assumption that the Standard Model is correct. It may still be possible to discover a Higgs boson above these masses, if it is accompanied by other particles beyond those accommodated by the Standard Model.<ref> {{cite journal |first1 = Michael E. |last1=Peskin |first2 = James D. |last2=Wells |year = 2001 |title = How can a heavy Higgs boson be consistent with the precision electroweak measurements? |journal= Physical Review D |volume = 64 |issue=9 |article-number=093003 |bibcode= 2001PhRvD..64i3003P |arxiv=hep-ph/0101342 |doi=10.1103/PhysRevD.64.093003 |s2cid=5932066 }} </ref>

The LHC cannot directly measure the Higgs boson's lifetime, due to its extreme brevity. It is predicted as {{val|1.56|e=-22|u=s}} based on the predicted [[decay width]] of {{val|4.07|e=-3|u=GeV}}.<ref name="LHCcrosssections"/> However it can be measured indirectly, based upon comparing masses measured from quantum phenomena occurring in the [[On shell and off shell|on shell]] production pathways and in the, much rarer, [[On shell and off shell|off shell]] production pathways, derived from Dalitz decay via a virtual photon {{nowrap|(H → γ*γ → ℓℓγ)}}. Using this technique, the lifetime of the Higgs boson was tentatively measured in 2021 as {{nowrap|1.2 – {{val|4.6|e=-22|u=s}}}}, at sigma 3.2 (1 in 1000) significance.<ref name="lifetime1"/><ref name="lifetime2-dalitz"/>

=== Production === {| class="wikitable floatright" style="text-align:center;" |+ [[Feynman diagram]]s for Higgs production |- |[[File:Higgs-gluon-fusion.svg|frameless|upright=.7|Gluon fusion]] ''Gluon fusion'' |[[File:Higgs-Higgsstrahlung.svg|frameless|upright=.7|Higgs Strahlung]] ''Higgs Strahlung'' |- |[[File:Higgs-WZ-fusion.svg|frameless|upright=.7|Vector boson fusion]] ''Vector boson fusion'' |[[File:Higgs-tt-fusion.svg|frameless|upright=.7|Top fusion]] ''Top fusion'' |}

If Higgs particle theories are valid, then a Higgs particle can be produced much like other particles that are studied, in a [[particle collider]]. This involves accelerating a large number of particles to extremely high energies and extremely close to the [[speed of light]], then allowing them to smash together. [[Proton]]s and lead [[ion]]s (the bare [[atomic nucleus|nuclei]] of lead [[atom]]s) are used at the LHC. In the extreme energies of these collisions, the desired esoteric particles will occasionally be produced and this can be detected and studied; any absence or difference from theoretical expectations can also be used to improve the theory. The relevant particle theory (in this case the Standard Model) will determine the necessary kinds of collisions and detectors. The Standard Model predicts that Higgs bosons could be formed in a number of ways,<ref name="HprodLHC"> {{cite journal |title=Higgs production at the lHC |first1=Julien |last1=Baglio |first2=Abdelhak |last2=Djouadi |journal=Journal of High Energy Physics |volume=1103 |year=2011 |page=055 |doi=10.1007/JHEP03(2011)055 |arxiv=1012.0530|bibcode = 2011JHEP...03..055B |issue=3 |s2cid=119295294 }}</ref><ref name="HprodTeva"> {{cite journal |title=Predictions for Higgs production at the Tevatron and the associated uncertainties |first1=Julien |last1=Baglio |first2=Abdelhak |last2=Djouadi |journal=Journal of High Energy Physics |volume=1010 |year=2010 |page=063 |doi=10.1007/JHEP10(2010)064 |arxiv=1003.4266 |bibcode = 2010JHEP...10..064B |issue=10 |s2cid=119199894 }}</ref><ref name="HprodLEP"> {{cite journal |title=Higgs boson searches at LEP |first=P. |last=Teixeira-Dias (LEP Higgs working group) |journal=Journal of Physics: Conference Series |volume=110 |year=2008 |article-number=042030 |doi=10.1088/1742-6596/110/4/042030 |arxiv=0804.4146 |bibcode = 2008JPhCS.110d2030T |issue=4 |s2cid=16443715 }}</ref> although the probability of producing a Higgs boson in any collision is always expected to be very small{{snd}}for example, only one Higgs boson per 10 billion collisions in the Large Hadron Collider.{{efn|name=production_rate}} The most common expected processes for Higgs boson production are: ; Gluon fusion : If the collided particles are [[hadron]]s such as the [[proton]] or [[antiproton]]{{snd}}as is the case in the LHC and Tevatron{{snd}}then it is most likely that two of the [[gluon]]s binding the hadron together collide. The easiest way to produce a Higgs particle is if the two gluons combine to form a loop of [[virtual particle|virtual]] quarks (see Feynman diagram). Since the coupling of particles to the Higgs boson is proportional to their mass, this process is more likely for heavy particles. In practice it is enough to consider the contributions of virtual [[top quark|top]] and [[bottom quark|bottom]] quarks (the heaviest quarks). This process is the dominant contribution at the LHC and Tevatron being about ten times more likely than any of the other processes.<ref name="HprodLHC" /><ref name="HprodTeva" /> ; Higgs Strahlung : If an elementary [[fermion]] collides with an anti-fermion{{snd}}e.g., a quark with an anti-quark or an [[electron]] with a [[positron]]{{snd}}the two can merge to form a virtual W or Z boson which, if it carries sufficient energy, can then emit a Higgs boson. This process was the dominant production mode at the LEP, where an electron and a positron collided to form a virtual Z boson, and it was the second largest contribution for Higgs production at the Tevatron. At the LHC this process is only the third largest, because the LHC collides protons with protons, making a quark-antiquark collision less likely than at the Tevatron. Higgs Strahlung is also known as ''associated production''.<ref name="HprodLHC" /><ref name="HprodTeva" /><ref name="HprodLEP" /> ; Weak boson fusion : Another possibility when two (anti-)fermions collide is that the two exchange a virtual W or Z boson, which emits a Higgs boson. The colliding fermions do not need to be the same type. So, for example, an [[up quark]] may exchange a Z boson with an anti-down quark. This process is the second most important for the production of Higgs particle at the LHC and LEP.<ref name="HprodLHC" /><ref name="HprodLEP" /> ; Top fusion : The final process that is commonly considered is by far the least likely (by two orders of magnitude). This process involves two colliding gluons, which each decay into a heavy quark–antiquark pair. A quark and antiquark from each pair can then combine to form a Higgs particle.<ref name="HprodLHC" /><ref name="HprodTeva" />

=== Decay === [[File:Higgsdecaywidth.svg|thumb|upright=1.3|The Standard Model prediction for the [[decay width]] of the Higgs particle depends on the value of its mass.]] Quantum mechanics predicts that if it is possible for a particle to decay into a set of lighter particles, then it will eventually do so.<ref> {{cite news |first=Lily |last=Asquith |date=22 June 2012 |title=Why does the Higgs decay? |department=Life and Physics |newspaper=[[The Guardian]] |location=London, UK |url=https://www.theguardian.com/science/life-and-physics/2012/jun/22/higgs-boson-particlephysics |url-status=live |access-date=14 August 2012 |archive-date=1 November 2013 |archive-url=https://web.archive.org/web/20131101014705/http://www.theguardian.com/science/life-and-physics/2012/jun/22/higgs-boson-particlephysics }} </ref> This is also true for the Higgs boson. The likelihood with which this happens depends on a variety of factors including: the difference in mass, the strength of the interactions, etc. Most of these factors are fixed by the Standard Model (SM), except for the mass of the Higgs boson itself. Given that the Higgs boson has a mass of {{val|125|u=GeV/c2}}, the SM then predicts a mean life time of about {{val|1.6|e=-22|u=s}}.{{efn|name=meanlife}}

[[File:HiggsBR.svg|thumb|upright=1.3|The Standard Model prediction for the [[branching ratio]]s of the different decay modes of the Higgs particle depends on the value of its mass.]] Since it interacts with all the massive elementary particles of the SM, the Higgs boson has many different processes through which it can decay. Each of these possible processes has its own probability, expressed as the ''[[branching ratio]]''; the fraction of the total number decays that follows that process. The SM predicts these branching ratios as a function of the Higgs mass (see [[#branching_plot_anchor|plot, right]]).

{{anchor|branching_plot_anchor}} [[File:HiggsDecays.png|thumb|upright=1.3|Higgs boson decays into (a) heavy vector boson pairs, (b) fermion–antifermion pairs, and (c,d) paired photons {{math|γγ}} or {{math|Zγ}}.<ref> {{cite journal |author=[[Compact Muon Solenoid|The CMS Collaboration]] |date=4 July 2022 |title=A portrait of the Higgs boson by the CMS experiment ten years after the discovery |journal=[[Nature (journal)|Nature]] |volume=607 |issue=7917 |pages=60–68 |doi=10.1038/s41586-022-04892-x |pmid=35788190 |pmc=9259501 |arxiv=2207.00043 |bibcode=2022Natur.607...60C |issn=1476-4687 |lang=en }} </ref>]] One way that the Higgs can decay is by splitting into a fermion–antifermion pair. As general rule, the Higgs is more likely to decay into heavy fermions than light fermions, because the mass of a fermion is proportional to the strength of its interaction with the Higgs.<ref name=PDGreview2012> {{cite web |title=Higgs bosons: theory and searches |date=12 July 2012 |website=PDGLive |series=[[Particle Data Group]] |publisher=[[Lawrence Berkeley Laboratory]] |url=http://pdg.lbl.gov/2012/reviews/rpp2012-rev-higgs-boson.pdf |url-status=live |access-date=15 August 2012 |archive-url=https://web.archive.org/web/20210308081640/https://pdg.lbl.gov/2012/reviews/rpp2012-rev-higgs-boson.pdf |archive-date=8 March 2021 }}</ref> By this logic the most common decay should be into a [[top quark|top]]–antitop quark pair. However, such a decay would only be possible if the Higgs were heavier than ~{{val|346|u=GeV/c2}}, twice the mass of the top quark. Given a Higgs mass of {{val|125|u=GeV/c2}}, the SM predicts that the most common decay is into a [[bottom quark|bottom]]–antibottom quark pair, which happens 57.7% of the time.<ref name=LHCcrosssections/> The second most common fermion decay at that mass is a [[tau particle|tau]]–antitau pair, which happens only about 6.3% of the time.<ref name=LHCcrosssections/>

Another possibility is for the Higgs to split into a pair of massive gauge bosons. The most likely possibility is for the Higgs to decay into a pair of W bosons (the light blue line in the plot), which happens about 21.5% of the time for a Higgs boson with a mass of {{val|125|u=GeV/c2}}.<ref name=LHCcrosssections/> The W bosons can subsequently decay either into a quark and an antiquark or into a charged lepton and a neutrino. The decays of W bosons into quarks are difficult to distinguish from the background, and the decays into leptons cannot be fully reconstructed (because neutrinos are impossible to detect in particle collision experiments). A cleaner signal is given by decay into a pair of Z bosons (which happens about 2.6% of the time for a Higgs with a mass of {{val|125|u=GeV/c2}}),<ref name=LHCcrosssections/> if each of the bosons subsequently decays into a pair of easy-to-detect charged leptons ([[electron]]s or [[muon]]s).

Decay into massless gauge bosons (i.e., [[gluon]]s or [[photon]]s) is also possible, but requires intermediate loop of virtual heavy quarks (top or bottom) or massive gauge bosons.<ref name=PDGreview2012/> The most common such process is the decay into a pair of gluons through a loop of virtual heavy quarks. This process, which is the reverse of the gluon fusion process mentioned above, happens approximately 8.6% of the time for a Higgs boson with a mass of {{val|125|u=GeV/c2}}. Much rarer is the decay into a pair of photons mediated by a loop of W bosons or heavy quarks, which happens only twice for every thousand decays.<ref name=LHCcrosssections/> However, this process is very relevant for experimental searches for the Higgs boson, because the energy and momentum of the photons can be measured very precisely, giving an accurate reconstruction of the mass of the decaying particle.<ref name=PDGreview2012/>

In 2021 the extremely rare [[Pion#Dalitz_decay_anchor|Dalitz decay]] was tentatively observed,{{cn|date=May 2024}} into two [[lepton]]s (electrons or muons) and a photon {{nobr|( {{math|ℓℓγ}} ),}} via [[virtual photon]] decay. This can happen in three ways: * Higgs to virtual photon to  {{math|ℓℓγ}}  in which the virtual photon {{nobr|( {{math|γ*}} )}} has very small but nonzero mass, * Higgs to Z boson to {{nobr| {{math|ℓℓγ}} ,}} * Higgs to two leptons, one of which emits a final-state photon leading to {{nobr| {{math|ℓℓγ}} .}} ATLAS searched for evidence of the first of these {{nobr|( {{math|H → γ*γ → ℓℓγ}} )}} for low lepton-pair masses {{nobr|( ≤ {{val|30|u=GeV/c2}} ),}} where this process should dominate. The observation is at [[statistical significance|significance]] 3.2 [[standard deviation|sigma]] (1 chance in 1000 of being wrong).<ref name=lifetime1/><ref name=lifetime2-dalitz/> This decay path is important because it facilitates measuring the [[on shell and off shell|on- and off-shell]] mass of the Higgs boson (allowing indirect measurement of decay time), and the decay into two charged particles allows exploration of [[charge conjugation]] and [[CP violation|charge parity (CP) violation]].<ref name=lifetime2-dalitz/>

=== Pair production === At the Large Hadron Collider (LHC), [[Higgs pair production|Higgs boson pair production]] occurs through several distinct mechanisms, similarly as single Higgs production:<ref>{{Cite journal |last1=Frederix |first1=R. |last2=Frixione |first2=S. |last3=Hirschi |first3=V. |last4=Maltoni |first4=F. |last5=Mattelaer |first5=O. |last6=Torrielli |first6=P. |last7=Vryonidou |first7=E. |last8=Zaro |first8=M. |date=2014-05-01 |title=Higgs pair production at the LHC with NLO and parton-shower effects |url=https://www.sciencedirect.com/science/article/pii/S0370269314001828 |journal=Physics Letters B |volume=732 |pages=142–149 |doi=10.1016/j.physletb.2014.03.026 |arxiv=1401.7340 |bibcode=2014PhLB..732..142F |issn=0370-2693}}</ref><ref>{{Cite journal |last1=Aad |first1=G. |last2=Abajyan |first2=T. |last3=Abbott |first3=B. |last4=Abdallah |first4=J. |last5=Abdel Khalek |first5=S. |last6=Abdelalim |first6=A. A. |last7=Abdinov |first7=O. |last8=Aben |first8=R. |last9=Abi |first9=B. |last10=Abolins |first10=M. |last11=AbouZeid |first11=O. S. |last12=Abramowicz |first12=H. |last13=Abreu |first13=H. |last14=Acharya |first14=B. S. |last15=Adamczyk |first15=L. |date=2012-09-17 |title=Observation of a new particle in the search for the Standard Model Higgs boson with the ATLAS detector at the LHC |url=https://www.sciencedirect.com/science/article/pii/S037026931200857X |journal=Physics Letters B |volume=716 |issue=1 |pages=1–29 |doi=10.1016/j.physletb.2012.08.020 |arxiv=1207.7214 |bibcode=2012PhLB..716....1A |hdl=10211.3/195341 |issn=0370-2693}}</ref>

* '''Gluon–gluon fusion (ggF)''' is the dominant production mode. It proceeds via loop diagrams involving heavy quarks, primarily the top quark, and includes both '''box''' and '''triangle''' topologies. The triangle diagram explicitly depends on the Higgs trilinear self-coupling, and its interference with the box diagram significantly affects the total cross section. * '''Vector boson fusion (VBF)''' involves the radiation of Higgs bosons from virtual W or Z bosons exchanged between incoming quarks. Although subdominant in rate, VBF offers distinctive event topologies and complementary sensitivity to new physics. * '''Associated production''' channels, such as '''ttHH''' (with top quark pairs) and '''VHH''' (with vector bosons), become increasingly important at higher center-of-mass energies and provide unique sensitivity to the Higgs-top and Higgs-gauge boson interactions.

Each of these production mechanisms offers different levels of sensitivity to the Higgs self-coupling λ, making them essential components in a comprehensive search for deviations from the Standard Model prediction.

Higgs boson pairs can decay through various channels. The most studied final states include:

* '''HH → bb̄bb̄''': Has the highest branching fraction (~34%) but suffers from large QCD background. * '''HH → bb̄γγ''': Low branching fraction (~0.3%) but excellent mass resolution due to clean photon identification. * '''HH → bb̄τ⁺τ⁻''': Offers a good compromise between signal rate and background contamination (~7.3% branching ratio).

The choice of decay mode affects the sensitivity of LHC experiments to the HH signal.

== Public discussion ==

=== Naming ===

==== Names used by physicists ==== The name most strongly associated with the particle and field is the Higgs boson<ref name=frank_close_infinity_puzzle/>{{rp|page=168}} and Higgs field. For some time the particle was known by a combination of its PRL author names (including at times Anderson), for example the Brout–Englert–Higgs particle, the Anderson–Higgs particle, or the Englert–Brout–Higgs–Guralnik–Hagen–Kibble mechanism,{{efn|name=other-names-used-note| Other names have included: * The "Anderson–Higgs" mechanism,<ref> {{cite journal | last1 = Liu | first1 = G.Z. | last2 = Cheng | first2 = G. | year = 2002 | title = Extension of the Anderson-Higgs mechanism | journal = Physical Review B | volume = 65 | issue = 13 | article-number = 132513 | doi = 10.1103/PhysRevB.65.132513 | arxiv = cond-mat/0106070 | bibcode = 2002PhRvB..65m2513L | citeseerx = 10.1.1.242.3601 | s2cid = 118551025 }} </ref> * "Higgs–Kibble" mechanism (by Abdus Salam)<ref name=frank_close_infinity_puzzle/> and * "A-B-E-G-H-H-K-'tH" mechanism [for Anderson, Brout, Englert, Guralnik, Hagen, Higgs, Kibble and 't Hooft] (by Peter Higgs).<ref name="frank_close_infinity_puzzle"/>}} and these are still used at times.<ref name=scholarpedia/><ref name="Nature-Higgs name"/> Fuelled in part by the issue of recognition and a potential shared Nobel Prize,<ref name="Nature-Higgs name"> {{cite journal |type=editorial |title=Mass appeal: As physicists close in on the Higgs boson, they should resist calls to change its name |date=21 March 2012 |journal=Nature |volume=483, 374 |issue=7390 |page=374 |doi=10.1038/483374a |doi-access=free |pmid=22437571 |bibcode = 2012Natur.483..374. }} </ref><ref name=Nova> {{cite web |last=Becker |first=Kate |date=29 March 2012 |title=A Higgs by any other name |department=Physics |series=NOVA |publisher=PBS |type=blog |url=https://www.pbs.org/wgbh/nova/physics/blog/2012/03/a-higgs-by-any-other-name |access-date=21 January 2013 |archive-url=https://web.archive.org/web/20121217014812/http://www.pbs.org/wgbh/nova/physics/blog/2012/03/a-higgs-by-any-other-name/ |archive-date=17 December 2012 }} </ref> the most appropriate name was still occasionally a topic of debate until 2013.<ref name="Nature-Higgs name"/> Higgs himself preferred to call the particle either by an acronym of all those involved, or "the scalar boson", or "the so-called Higgs particle".<ref name=Nova/>

A considerable amount has been written on how Higgs's name came to be exclusively used. Two main explanations are offered. The first is that Higgs undertook a step which was either unique, clearer or more explicit in his paper in formally predicting and examining the particle. Of the PRL papers' authors, only the paper by Higgs ''explicitly'' offered as a prediction that a massive particle would exist and calculated some of its properties;<ref name=CERNHiggsFAQ> {{cite news |title=Frequently asked questions: The Higgs! |year=2012 |website=CERN Bulletin |issue=28 |url=http://cdsweb.cern.ch/journal/CERNBulletin/2012/28/News%20Articles/1459456?ln=en |access-date=18 July 2012 |url-status=live |archive-url=https://web.archive.org/web/20120705200336/http://cdsweb.cern.ch/journal/CERNBulletin/2012/28/News%20Articles/1459456?ln=en |archive-date=5 July 2012 }} </ref><ref name=frank_close_infinity_puzzle/>{{rp|page=167}} he was therefore "the first to postulate the existence of a massive particle" according to ''[[Nature (journal)|Nature]]''.<ref name="Nature-Higgs name"/> Physicist and author [[Frank Close]] and physicist-blogger [[Peter Woit]] both comment that the paper by GHK was also completed after Higgs and Brout–Englert were submitted to [[Physical Review Letters]],<ref name=woit2013> {{cite web |first=Peter |last=Woit |date=13 April 2013 |title=''"Not even wrong"'': Anderson on Anderson-Higgs |type=blog |website=Woit's physics blog |publisher=[[Columbia University]] |place=New York, NY |department=Mathematics |url=http://www.math.columbia.edu/~woit/wordpress/?p=5753 |access-date=6 August 2013 |url-status=live |archive-date=19 October 2013 |archive-url=https://web.archive.org/web/20131019153644/http://www.math.columbia.edu/~woit/wordpress/?p=5753 }} </ref><ref name=frank_close_infinity_puzzle/>{{rp|page=167}} and that Higgs alone had drawn attention to a predicted massive ''scalar'' boson, while all others had focused on the massive ''vector'' bosons.<ref name=woit2013/><ref name=frank_close_infinity_puzzle/>{{rp|page=154,166,175}} In this way, Higgs's contribution also provided experimentalists with a crucial "concrete target" needed to test the theory.<ref> {{cite news |last=Sample |first=Ian |date=4 July 2012 |title=Higgs boson's many great minds cause a Nobel prize headache |newspaper=[[The Guardian]] |location=London, UK |url=https://www.theguardian.com/science/2012/jul/04/higgs-boson-nobel-prize-headache |access-date=23 July 2013 |url-status=live |archive-url=https://web.archive.org/web/20131017105735/http://www.theguardian.com/science/2012/jul/04/higgs-boson-nobel-prize-headache |archive-date=17 October 2013 }} </ref>

However, in Higgs's view, Brout and Englert did not explicitly mention the boson since its existence is plainly obvious in their work,<ref name=MyLifeAsABoson/>{{rp|page=6}} while according to Guralnik the GHK paper was a complete analysis of the entire symmetry breaking mechanism whose [[mathematical rigour]] is absent from the other two papers, and a massive particle may exist in some solutions.<ref name="Guralnik 2009"/>{{rp|page=9}} Higgs's paper also provided an "especially sharp" statement of the challenge and its solution according to [[history of science|science historian]] David Kaiser.<ref name=Nova/>

The alternative explanation is that the name was popularised in the 1970s due to its use as a convenient shorthand or because of a mistake in citing. Many accounts {{big|(}}including Higgs's own<ref name=MyLifeAsABoson/>{{rp|page=7}}{{big|)}} credit the "Higgs" name to physicist [[Benjamin W. Lee|Benjamin Lee]].{{efn| [[Benjamin W. Lee]] also uses the [[Korean language]] name ''[[Benjamin W. Lee|Lee Whi-soh]]''. }} Lee was a significant populariser of the theory in its early days, and habitually attached the name "Higgs" as a "convenient shorthand" for its components from 1972,<ref name=ISample29052009/><ref name="Nature-Higgs name"/><ref name=Peskin> {{cite web |last = Peskin |first = M. |date = July 2012 |title = 40 years of the Higgs boson |website = Presentation at SSI 2012 |publisher = [[Stanford University]] |department = 2012 [[Stanford Linear Accelerator|SLAC]] Summer Institute Conferences |pages = 3–5 |url = http://www-conf.slac.stanford.edu/ssi/2012/Presentations/Peskin.pdf |access-date = 21 January 2013 |url-status = live |archive-date = 1 May 2014 |archive-url = https://web.archive.org/web/20140501135850/http://www-conf.slac.stanford.edu/ssi/2012/Presentations/Peskin.pdf |quote = quoting Lee's ICHEP 1972 presentation at Fermilab: "... which is known as the Higgs mechanism ..." and "Lee's locution" – his footnoted explanation of this shorthand. }} </ref><ref> {{cite press release |title=Nobelist Steven Weinberg praises professor Carl Hagen and collaborators for Higgs Boson theory |date=8 October 2007 |publisher=[[University of Rochester]] |url=http://www.pas.rochester.edu/urpas/news/Hagen_030708 |archive-url=https://web.archive.org/web/20080416064136/http://www.pas.rochester.edu/urpas/news/Hagen_030708 |archive-date=16 April 2008 |author=University of Rochester Physics & Astronomy press office |place=Rochester, New York |department=Department of Physics and Astronomy}} University of Rochester Hagen Sakurai Prize announcement. </ref><ref> {{cite AV media | last = Hagen | first = C.R. | date = 2010 | title = Sakurai Prize talk | medium = video | via = YouTube | url = https://www.youtube.com/watch?v=QrCPrwRBi7E&feature=PlayList&p=BDA16F52CA3C9B1D&playnext_from=PL&index=9 }} </ref> and in at least one instance from as early as 1966.{{refn|name=Lee_Weinberg_2012_name}} Although Lee clarified in his footnotes that "'Higgs' is an abbreviation for Higgs, Kibble, Guralnik, Hagen, Brout, Englert",<ref name=Peskin/> his use of the term (and perhaps also Steven Weinberg's mistaken cite of Higgs's paper as the first in his seminal 1967 paper<ref name=frank_close_infinity_puzzle/><ref name="New York Review 2012"> {{cite news |last=Weinberg |first=Steven |date=10 May 2012 |title=The crisis of big science |newspaper=[[The New York Review of Books]] |at=footnote 1 |url=http://www.nybooks.com/articles/archives/2012/may/10/crisis-big-science/?pagination=false |access-date=12 February 2013 |url-status=live |archive-date=21 January 2013 |archive-url=https://web.archive.org/web/20130121143729/http://www.nybooks.com/articles/archives/2012/may/10/crisis-big-science/?pagination=false }} </ref>{{refn |name=Lee_Weinberg_2012_name | {{cite journal |last1=Cho |first1=A. |date=14 September 2012 |title=Why the 'Higgs'? |journal=Science |department=Particle physics |volume=337 |issue=6100 |page=1287 |doi=10.1126/science.337.6100.1287 |pmid=22984044 |url=http://211.144.68.84:9998/91keshi/Public/File/41/337-6100/pdf/1287.full.pdf |access-date=12 February 2013 |archive-url=http://webarchive.nationalarchives.gov.uk/20130704110735/http://211.144.68.84:9998/91keshi/Public/File/41/337-6100/pdf/1287.full.pdf |archive-date=4 July 2013 |quote=Lee ... apparently used the term 'Higgs boson' as early as 1966 ... but what may have made the term stick is a seminal paper Steven Weinberg ... published in 1967 ... Weinberg acknowledged the mix-up in an essay in the ''New York Review of Books'' in May 2012. }} (See also original article in * ''[[New York Review of Books]]'' (2012)<ref name="New York Review 2012"/> * {{cite book |first=Frank |last=Close |author-link=Frank Close |year=2011 |title=The Infinity Puzzle |page=372 |section=['''see book extract'''] |publisher=Oxford University Press |section-url=https://books.google.com/books?id=EDySwmXOEhMC&q=unintended+consequence+for+history |via=Google Books }})<ref name="frank_close_infinity_puzzle"/> which identified the error). }}) meant that by around 1975–1976 others had also begun to use the name "Higgs" exclusively as a shorthand.{{efn|name=early-use-of-name-Higgs-boson| Examples of early papers using the term ''"Higgs boson"'' include * Ellis, Gaillard, & Nanopoulos (1976) "A phenomenological profile of the Higgs boson". * Bjorken (1977) "Weak interaction theory and neutral currents". * Wienberg (received, 1975) "Mass of the Higgs boson". }} In 2012, physicist [[Frank Wilczek]], who was credited for naming the elementary particle, the [[axion]] (over an alternative proposal "Higglet", by Weinberg), endorsed the "Higgs boson" name, stating "History is complicated, and wherever you draw the line, there will be somebody just below it."<ref name=Nova/>

==== Nickname ==== The Higgs boson is often referred to as the "God particle" in popular media outside the scientific community.<ref> {{cite book |first1=Leon |last1=Lederman |author-link1=Leon M. Lederman |first2=Dick |last2=Teresi |author-link2=Dick Teresi |year=2006 |title=The God Particle: If the universe is the answer, what is the question? |publisher=Houghton Mifflin Harcourt |isbn=978-0-547-52462-7 |url=https://books.google.com/books?id=jMOOQDHxWyIC |access-date=27 June 2015 |url-status=live |archive-url=https://web.archive.org/web/20160513093132/https://books.google.com/books?id=jMOOQDHxWyIC |archive-date=13 May 2016 }} </ref><ref> {{cite news |first=Kelly |last=Dickerson |date=8 September 2014 |title=Stephen Hawking says 'god particle' could wipe out the universe |publisher=livescience.com |url=http://www.livescience.com/47737-stephen-hawking-higgs-boson-universe-doomsday.html |access-date=23 February 2015 |url-status=live |archive-url=https://web.archive.org/web/20150128090232/http://www.livescience.com/47737-stephen-hawking-higgs-boson-universe-doomsday.html |archive-date=28 January 2015 }} </ref><ref> {{cite book |first=Jim |last=Baggott |author-link=Jim Baggott |year=2012 |title=Higgs: The invention and discovery of the 'God particle' |publisher=Oxford University Press |isbn=978-0-19-165003-1 |url=https://books.google.com/books?id=yVQMqgZrPt4C |access-date=27 June 2015 |url-status=live |archive-url=https://web.archive.org/web/20160520032714/https://books.google.com/books?id=yVQMqgZrPt4C |archive-date=20 May 2016 }} </ref><ref> {{cite book |title=The Higgs Boson: Searching for the God Particle |year=2012 |publisher=Scientific American / Macmillan |isbn=978-1-4668-2413-3 |url=https://books.google.com/books?id=6Rv3-37b8wUC |access-date=27 June 2015 |url-status=live |archive-url=https://web.archive.org/web/20160609220919/https://books.google.com/books?id=6Rv3-37b8wUC |archive-date=9 June 2016 }} </ref><ref> {{cite book |author=Jaeckel, Ted |year=2007 |title=The God Particle: The discovery and modeling of the ultimate prime particle |publisher=Universal-Publishers |isbn=978-1-58112-959-5 |url=https://books.google.com/books?id=C4xPoGjvgBgC |access-date=27 June 2015 |url-status=live |archive-url=https://web.archive.org/web/20160429200844/https://books.google.com/books?id=C4xPoGjvgBgC |archive-date=29 April 2016 }} </ref> The nickname comes from the title of the 1993 book on the Higgs boson and particle physics, ''[[The God Particle: If the Universe Is the Answer, What Is the Question?]]'' by [[Nobel Prize for Physics|Physics Nobel Prize winner]] and [[Fermilab]] director [[Leon M. Lederman]].<ref name="L&T"> {{cite book |first1=Leon M. |last1=Lederman |author-link1=Leon M. Lederman |first2=Dick |last2=Teresi |year=1993 |title=The God Particle: If the universe is the answer, what is the question |publisher=Houghton Mifflin Company |isbn=978-0-395-55849-2 |url=https://archive.org/details/godparticleifthe00lede |url-access=registration }} </ref> Lederman wrote it in the context of failing US government support for the [[Superconducting Super Collider]],<ref name="SSC LA Times"/> a partially constructed titanic<ref> {{cite news |title=A supercompetition for Illinois |date=31 October 1986 |newspaper=[[Chicago Tribune]] |url=https://www.chicagotribune.com/1986/10/31/a-supercompetition-for-illinois/ |access-date=16 January 2013 |url-status=live |archive-url=https://web.archive.org/web/20130515065951/http://articles.chicagotribune.com/1986-10-31/news/8603220012_1_illinois-electron-volts-high-energy |archive-date=15 May 2013 |quote=The SSC, proposed by the U.S. Department of Energy in 1983, is a mind-bending project ... this gigantic laboratory ... this titanic project }}</ref><ref> {{cite news |last=Diaz |first=Jesus |date=15 December 2012 |title=This is [the] world's largest super collider that never was |website=Gizmodo |url=https://gizmodo.com/5968784/this-is-worlds-largest-super-collider-that-never-was |access-date=16 January 2013 |url-status=live |archive-url=https://web.archive.org/web/20130118195319/http://gizmodo.com/5968784/this-is-worlds-largest-super-collider-that-never-was |archive-date=18 January 2013 |quote=... this titanic complex ...}}</ref> competitor to the [[Large Hadron Collider]] with planned collision energies of {{nowrap|2 × 20 TeV}} that was championed by Lederman since its 1983 inception<ref name="SSC LA Times"> {{cite news |last=Aschenbach |first=Joy |date=5 December 1993 |title=No resurrection in sight for moribund super collider |department=Science |newspaper=[[Los Angeles Times]] |url=https://www.latimes.com/archives/la-xpm-1993-12-05-mn-64100-story.html |access-date=16 January 2013 |url-status=live |archive-url=https://web.archive.org/web/20131106045723/http://articles.latimes.com/1993-12-05/news/mn-64100_1_superconducting-super-collider |archive-date=6 November 2013 }}</ref>{{efn|Global financial partnerships could be the only way to salvage such a project. Some feel that Congress delivered a fatal blow.

"We have to keep the momentum and optimism and start thinking about international collaboration," said Leon M. Lederman, the Nobel Prize-winning physicist who was the architect of the super collider plan.<ref name="SSC LA Times"/>}}<ref name="Illinois Issues 1987"> {{cite news |last=Abbott |first=Charles |date=June 1987 |title=Super competition for superconducting super collider |journal=Illinois Issues Journal |page=18 |url=http://www.lib.niu.edu/1987/ii8706tc.html |access-date=16 January 2013 |url-status=live |archive-url=https://web.archive.org/web/20131101223228/http://www.lib.niu.edu/1987/ii8706tc.html |archive-date=1 November 2013 |quote=Lederman, who considers himself an unofficial propagandist for the super collider, said the SSC could reverse the physics brain drain in which bright young physicists have left America to work in Europe and elsewhere. }}</ref><ref name="Caltech"> {{cite journal |last=Kevles |first=Dan |date=Winter 1995 |journal=Engineering & Science |volume=58 |issue=2 |pages=16–25 |publisher=[[California Institute of Technology]] |url=http://calteches.library.caltech.edu/568/1/ES58.2.1995.pdf |title=Good-bye to the SSC: On the life and death of the superconducting super collider |access-date=16 January 2013 |url-status=live |archive-url=https://web.archive.org/web/20130511120537/http://calteches.library.caltech.edu/568/1/ES58.2.1995.pdf |archive-date=11 May 2013 |quote=Lederman, one of the principal spokesmen for the SSC, was an accomplished high-energy experimentalist who had made Nobel Prize-winning contributions to the development of the Standard Model during the 1960s (although the prize itself did not come until 1988). He was a fixture at congressional hearings on the collider, an unbridled advocate of its merits. }}</ref> and shut down in 1993. The book sought in part to promote awareness of the significance and need for such a project in the face of its possible loss of funding.<ref name="Calder 2005"> {{cite book |last=Calder |first=Nigel |author-link=Nigel Calder |year=2005 |title=Magic Universe: A grand tour of modern science |pages=369–370 |publisher=OUP Oxford |isbn=978-0-19-162235-9 |url=https://books.google.com/books?id=E4NfZ9FDcc8C&pg=PA370 |access-date=5 September 2020 |url-status=live |archive-url=https://web.archive.org/web/20220125094450/https://books.google.com/books?id=E4NfZ9FDcc8C&pg=PA370 |archive-date=25 January 2022 |quote=The possibility that the next big machine would create the Higgs became a carrot to dangle in front of funding agencies and politicians. A prominent American physicist, Leon lederman [sic], advertised the Higgs as The God Particle in the title of a book published in 1993{{nbsp}}[...] Lederman was involved in a campaign to persuade the US government to continue funding the Superconducting Super Collider{{nbsp}}[...] the ink was not dry on Lederman's book before the US Congress decided to write off the billions of dollars already spent }}</ref> Lederman, a leading researcher in the field, writes that he wanted to title his book ''The Goddamn Particle: If the Universe is the Answer, What is the Question?'' Lederman's editor decided that the title was too controversial and convinced him to change the title to ''The God Particle: If the Universe is the Answer, What is the Question?''<ref name=goddamnparticleoffensive> {{cite book |last1=Lederman |first1=Leon |author-link1=Leon M. Lederman |year=1993 |title=The God Particle: If the universe is the answer, what is the question? |at=chapter 2, page 2 |publisher=Dell Publishing |isbn=978-0-385-31211-0 |url=https://archive.org/details/godparticle00leon |url-access=registration |access-date=30 July 2015 }}</ref>

While media use of this term may have contributed to wider awareness and interest,<ref> {{cite news |author=McGrath |first=Alister |author-link=Alister McGrath |date=15 December 2011 |title=Higgs boson: The particle of faith |url=https://www.telegraph.co.uk/science/8956938/Higgs-boson-the-particle-of-faith.html |archive-url=https://web.archive.org/web/20111215120632/https://www.telegraph.co.uk/science/8956938/Higgs-boson-the-particle-of-faith.html |archive-date=15 December 2011 |access-date=15 December 2011 |newspaper=[[The Daily Telegraph]]}}</ref> many scientists feel the name is inappropriate<ref name=ISample29052009/><ref name=NatPost/><ref name=ISample03032009> {{cite news |first=Ian |last=Sample |date=3 March 2009 |title=Father of the god particle: Portrait of Peter Higgs unveiled |newspaper=[[The Guardian]] |location=London, UK |url=https://www.theguardian.com/science/blog/2009/mar/02/god-particle-peter-higgs-portrait-lhc |access-date=24 June 2009 |url-status=live |archive-url=https://web.archive.org/web/20140912002536/http://www.theguardian.com/science/blog/2009/mar/02/god-particle-peter-higgs-portrait-lhc |archive-date=12 September 2014 }}</ref> since it is sensational [[hyperbole]] and misleads readers;<ref name=nickname-telegraph> {{cite news |last=Chivers |first=Tom |date=13 December 2011 |title=How the 'God particle' got its name |newspaper=[[The Daily Telegraph|The Telegraph]] |location=London, UK |url=http://blogs.telegraph.co.uk/news/tomchiversscience/100123765/how-the-god-particle-got-its-name/ |access-date=3 December 2012 |archive-url=https://web.archive.org/web/20120109062930/http://blogs.telegraph.co.uk/news/tomchiversscience/100123765/how-the-god-particle-got-its-name/ |archive-date=9 January 2012 }}</ref> the particle also has nothing to do with any God, leaves open numerous [[unanswered questions in physics|questions in fundamental physics]], and does not explain the ultimate [[origin of the universe]]. [[Peter Higgs|Higgs]], an [[atheist]], was reported to be displeased and stated in a 2008 interview that he found it "embarrassing" because it was "the kind of misuse{{nbsp}}[...] which I think might offend some people".<ref name=nickname-telegraph/><ref name=nickname-reuters> {{cite news |title=Key scientist sure "God particle" will be found soon |date=7 April 2008 |website=[[Reuters News Service]] |url=https://www.reuters.com/article/scienceNews/idUSL0765287220080407?sp=true |access-date=2 July 2017 |url-status=live |archive-url=https://web.archive.org/web/20210223193233/https://www.reuters.com/article/scienceNews/idUSL0765287220080407?sp=true |archive-date=23 February 2021 }}</ref><ref name=NS> {{cite magazine |title=The man behind the 'God particle' |date=13 September 2008 |magazine=[[New Scientist]] |pages=44–45 |type=interview |url=https://www.newscientist.com/channel/opinion/mg19926732.100-interview-the-man-behind-the-god-particle.html |access-date=29 August 2017 |url-status=live |archive-url=https://web.archive.org/web/20080913214154/http://www.newscientist.com/channel/opinion/mg19926732.100-interview-the-man-behind-the-god-particle.html |archive-date=13 September 2008 }}; original interview: {{cite news |title=Father of the 'God particle' |date=30 June 2008 |newspaper=[[The Guardian]] |url=https://www.theguardian.com/science/2008/jun/30/higgs.boson.cern |access-date=14 December 2016 |url-status=live |archive-url=https://web.archive.org/web/20161201180117/https://www.theguardian.com/science/2008/jun/30/higgs.boson.cern |archive-date=1 December 2016 }}</ref> The nickname has been satirised in mainstream media as well.<ref> {{cite magazine |last=Borowitz |first=Andy |author-link=Andy Borowitz |date=13 July 2012 |title=5 questions for the Higgs boson |magazine=[[The New Yorker]] |url=https://newyorker.com/humor/borowitz-report/5-questions-for-the-higgs-boson |access-date=12 December 2019 |url-status=live |archive-url=https://web.archive.org/web/20201112000412/https://www.newyorker.com/humor/borowitz-report/5-questions-for-the-higgs-boson |archive-date=12 November 2020 }}</ref> Science writer Ian Sample stated in his 2010 book on the search that the nickname is "universally hate[d]" by physicists and perhaps the "worst derided" in the [[history of physics]], but that (according to Lederman) the publisher rejected all titles mentioning "Higgs" as unimaginative and too unknown.<ref> {{cite book |last=Sample |first=Ian |year=2010 |title=Massive: The hunt for the God particle |pages=148–149, 278–279 |publisher=Virgin Books |isbn=978-1-905264-95-7 |url=https://books.google.com/books?id=GuhAP7YCcuoC&pg=PA148 |access-date=5 September 2020 |url-status=live |archive-url=https://web.archive.org/web/20220125094530/https://books.google.com/books?id=GuhAP7YCcuoC&pg=PA148 |archive-date=25 January 2022 }}</ref>

Lederman begins with a review of the long human search for knowledge, and explains that his tongue-in-cheek title draws an analogy between the impact of the Higgs field on the fundamental symmetries at the [[Big Bang]], and the apparent chaos of structures, particles, forces and interactions that resulted and shaped our present universe, with the biblical story of [[Tower of Babel|Babel]] in which the primordial single language of early [[Book of Genesis|Genesis]] was [[confusion of tongues|fragmented into many disparate languages]] and cultures.<ref> {{cite news |last=Cole |first=K. |date=14 December 2000 |title=One thing is perfectly clear: Nothingness is perfect |department=Science File |newspaper=[[Los Angeles Times]] |url=https://www.latimes.com/archives/la-xpm-2000-dec-14-me-65457-story.html |access-date=17 January 2013 |url-status=live |archive-url=https://web.archive.org/web/20151005152515/http://articles.latimes.com/2000/dec/14/local/me-65457 |archive-date=5 October 2015 |quote=Consider the early universe–a state of pure, perfect nothingness; a formless fog of undifferentiated stuff{{nbsp}}[...] 'perfect symmetry'{{nbsp}}[...] What shattered this primordial perfection? One likely culprit is the so-called Higgs field{{nbsp}}[...] Physicist Leon Lederman compares the way the Higgs operates to the biblical story of Babel [whose citizens] all spoke the same language{{nbsp}}[...] Like God, says Lederman, the Higgs differentiated the perfect sameness, confusing everyone (physicists included){{nbsp}}[...] [Nobel Prizewinner Richard] [[Richard Feynman|Feynman]] wondered why the universe we live in was so obviously askew{{nbsp}}[...] Perhaps, he speculated, total perfection would have been unacceptable to God. And so, just as God shattered the perfection of Babel, 'God made the laws only nearly symmetrical' }}</ref>

{{blockquote|Today{{nbsp}}[...] we have the standard model, which reduces all of reality to a dozen or so particles and four forces{{nbsp}}[...] It's a hard-won simplicity [and] remarkably accurate. But it is also incomplete and, in fact, internally inconsistent{{nbsp}}[...] This boson is so central to the state of physics today, so crucial to our final understanding of the structure of matter, yet so elusive, that I have given it a nickname: the God Particle. Why God Particle? Two reasons. One, the publisher wouldn't let us call it the Goddamn Particle, though that might be a more appropriate title, given its villainous nature and the expense it is causing. And two, there is a connection, of sorts, to [[Book of Genesis|another book]], a {{em|much}} older one ...|Lederman & Teresi<ref name="L&T"/>{{rp|page=22}}}}

Lederman asks whether the Higgs boson was added just to perplex and confound those seeking knowledge of the universe, and whether physicists will be confounded by it as recounted in that story, or ultimately surmount the challenge and understand "how beautiful is the universe [God has] made".<ref>Lederman, p. 22 ''et seq''.: "Something we cannot yet detect and which, one might say, has been put there to test and confuse us{{nbsp}}[...] The issue is whether physicists will be confounded by this puzzle or whether, in contrast to the unhappy Babylonians, we will continue to build the tower and, as Einstein put it, "know the mind of God".

"And the Lord said, Behold the people are un-confounding my confounding. And the Lord sighed and said, Go to, let us go down, and there give them the God Particle so that they may see how beautiful is the universe I have made."</ref>

==== Other proposals ==== A renaming competition by British newspaper ''[[The Guardian]]'' in 2009 resulted in their science correspondent choosing the name "the [[champagne bottle]] boson" as the best submission: "The bottom of a champagne bottle is in the shape of the [[Higgs potential]] and is often used as an illustration in physics lectures. So it's not an embarrassingly grandiose name, it is memorable, and [it] has some physics connection too."<ref> {{cite news |first=Ian |last=Sample |date=12 June 2009 |title=Higgs competition: Crack open the bubbly, the God particle is dead |newspaper=[[The Guardian]] |location=London, UK |url=https://www.theguardian.com/science/blog/2009/jun/05/cern-lhc-god-particle-higgs-boson |access-date=4 May 2010 |url-status=live |archive-url=https://web.archive.org/web/20150112040433/http://www.theguardian.com/science/blog/2009/jun/05/cern-lhc-god-particle-higgs-boson |archive-date=12 January 2015 }} </ref> The name ''Higgson'' was suggested as well, in an opinion piece in the [[Institute of Physics]]' online publication ''physicsworld.com''.<ref> {{cite news |first=Fraser |last=Gordon |date=5 July 2012 |title=Introducing the higgson |website=physicsworld.com |url=http://physicsworld.com/cws/article/indepth/2012/jul/04/introducing-the-higgson |access-date=25 August 2012 |url-status=live |archive-url=https://web.archive.org/web/20120708234444/http://physicsworld.com/cws/article/indepth/2012/jul/04/introducing-the-higgson |archive-date=8 July 2012 }} </ref>

=== Educational explanations and analogies === [[File:Light dispersion of a mercury-vapor lamp with a flint glass prism IPNr°0125.jpg|thumb|Photograph of light passing through a [[dispersive prism]]: the rainbow effect arises because [[photon]]s are not all affected to the same degree by the dispersive material of the prism.]] There has been considerable public discussion of analogies and explanations for the Higgs particle and how the field creates mass,<ref> {{cite news |last=Wolchover |first=Natalie |author-link=Natalie Wolchover |date=3 July 2012 |title=Higgs boson explained: How the 'God particle' gives things mass |website=[[Huffington Post]] |url=https://huffingtonpost.com/2012/07/03/higgs-boson-explained-god-particle_n_1645732.html |access-date=21 January 2013 |url-status=live |archive-url=https://web.archive.org/web/20130420011323/http://www.huffingtonpost.com/2012/07/03/higgs-boson-explained-god-particle_n_1645732.html |archive-date=20 April 2013 }} </ref><ref> {{cite news |last=Oliver |first=Laura |date=4 July 2012 |title=Higgs boson: How would you explain it to a seven-year-old? |newspaper=[[The Guardian]] |location=London, UK |url=https://www.theguardian.com/science/2012/jul/04/higgs-boson-readers-explain |access-date=21 January 2013 |url-status=live |archive-url=https://web.archive.org/web/20141022212624/http://www.theguardian.com/science/2012/jul/04/higgs-boson-readers-explain |archive-date=22 October 2014 }} </ref> including coverage of explanatory attempts in their own right and a competition in 1993 for the best popular explanation by then-UK Minister for Science [[William Waldegrave, Baron Waldegrave of North Hill|Sir William Waldegrave]]<ref> {{cite news |last=Zimmer |first=Ben |author-link=Ben Zimmer |date=15 July 2012 |title=Higgs boson metaphors as clear as molasses |newspaper=[[The Boston Globe]] |url=https://www.bostonglobe.com/ideas/2012/07/14/metaphors-and-higgs-boson/UjdsEySmG63XIAcNN7LNSO/story.html |access-date=21 January 2013 |url-status=live |archive-url=https://web.archive.org/web/20130204021345/http://www.bostonglobe.com/ideas/2012/07/14/metaphors-and-higgs-boson/UjdsEySmG63XIAcNN7LNSO/story.html |archive-date=4 February 2013 }} </ref> and articles in newspapers worldwide.

An educational collaboration involving an LHC physicist and a [http://teachers.web.cern.ch/teachers/ High School Teachers at CERN] educator suggests that [[Dispersion (optics)|dispersion of light]]{{snd}}responsible for the [[rainbow]] and [[dispersive prism]]{{snd}}is a useful analogy for the Higgs field's symmetry breaking and mass-causing effect.<ref>{{cite web|title=The Higgs particle: an analogy for Physics classroom (section) |publisher=www.lhc-closer.es (a collaboration website of LHCb physicist Xabier Vidal and High School Teachers and CERN educator Ramon Manzano) |url=http://www.lhc-closer.es/php/index.php?i=1&s=6&p=5&e=0 |access-date=9 January 2013 |url-status=live |archive-url=https://web.archive.org/web/20120705043620/http://www.lhc-closer.es/php/index.php?i=1&s=6&p=5&e=0 |archive-date=5 July 2012}}</ref>

{| class="wikitable" style="font-size:90%" |- | '''Symmetry breaking in optics''' || In vacuum, light of all colours (or [[photon]]s of all [[wavelength]]s) travels at [[speed of light|the same velocity]], a symmetrical situation. In some substances such as glass, water or air, this symmetry is broken ''(See: [[Photon#In matter|Photons in matter]])''. The result is that light of different wavelengths have [[Speed of light#In a medium|different velocities]]. |- | '''{{nowrap|Symmetry breaking in particle physics}}''' || In "naive" gauge theories, gauge bosons and other fundamental particles are all massless{{snd}}also a symmetrical situation. In the presence of the Higgs field this symmetry is broken. The result is that particles of different types will have different masses. |}

Matt Strassler uses electric fields as an analogy:<ref>{{cite news |last=Flam|first=Faye |author-link=Faye Flam |date=12 July 2012 |title=Finally – a Higgs boson story anyone can understand |newspaper=[[The Philadelphia Inquirer]] (philly.com) |url=http://www.philly.com/philly/blogs/evolution/Finally---A-Higgs-Boson-Story-Anyone-Can-Understand.html |access-date=21 January 2013|url-status=live |archive-url=https://web.archive.org/web/20130323033258/http://www.philly.com/philly/blogs/evolution/Finally---A-Higgs-Boson-Story-Anyone-Can-Understand.html |archive-date=23 March 2013}}</ref>

{{blockquote|Some particles interact with the Higgs field while others don't. Those particles that feel the Higgs field act as if they have mass. Something similar happens in an [[electric field]] – charged objects are pulled around and neutral objects can sail through unaffected. So you can think of the Higgs search as an attempt to make waves in the Higgs field [''create Higgs bosons''] to prove it's really there.}}

A similar explanation was offered by ''[[The Guardian]]'':<ref> {{cite news |last=Sample |first=Ian |date=28 April 2011 |title=How will we know when the Higgs particle has been detected? |newspaper=[[The Guardian]] |location=London, UK |url=https://www.theguardian.com/science/2011/apr/28/higgs-boson-rumour-cern-lhc |access-date=21 January 2013 |url-status=live |archive-url=https://web.archive.org/web/20160126044115/http://www.theguardian.com/science/2011/apr/28/higgs-boson-rumour-cern-lhc |archive-date=26 January 2016 }} </ref>

{{blockquote|The Higgs boson is essentially a ripple in a field said to have emerged at the birth of the universe and to span the cosmos to this day ... The particle is crucial however: It is the [[smoking gun]], the evidence required to show the theory is right.}}

The Higgs field's effect on particles was famously described by physicist David Miller as akin to a room full of political party workers spread evenly throughout a room: The crowd gravitates to and slows down famous people but does not slow down others.{{efn| 1=In Miller's analogy, the Higgs field is compared to political party workers spread evenly throughout a room. There will be some people (in Miller's example an anonymous person) who pass through the crowd with ease, paralleling the interaction between the field and particles that do not interact with it, such as massless photons. There will be other people (in Miller's example the British prime minister) who would find their progress being continually slowed by the swarm of admirers crowding around, paralleling the interaction for particles that do interact with the field and by doing so, acquire a finite mass.<ref name="Miller analogy"/><ref> {{cite news |first=Kathryn |last=Jepsen |date=1 March 2012 |title=Ten things you may not know about the Higgs boson |website=[[Symmetry Magazine]] |url=http://www.symmetrymagazine.org/cms/?pid=1000921 |access-date=10 July 2012 |archive-url=https://web.archive.org/web/20120814205924/http://www.symmetrymagazine.org/cms/?pid=1000921 |archive-date=14 August 2012 }} </ref> }} He also drew attention to well-known effects in [[solid state physics]] where an electron's effective mass can be much greater than usual in the presence of a crystal lattice.<ref name="Miller analogy"> {{cite web |first=David |last=Miller |year=1993 |title=A quasi-political explanation of the Higgs boson; for Mr. Waldegrave, UK Science Minister |url=http://www.hep.ucl.ac.uk/~djm/higgsa.html |access-date=10 July 2012 |url-status=live |archive-url=https://web.archive.org/web/20100315103707/http://www.hep.ucl.ac.uk/~djm/higgsa.html |archive-date=15 March 2010 }} </ref>

Analogies based on [[Drag (physics)|drag]] effects, including analogies of "[[syrup]]" or "[[molasses]]" are also well known, but can be somewhat misleading since they may be understood (incorrectly) as saying that the Higgs field simply resists some particles' motion but not others'{{snd}}a simple resistive effect could also conflict with [[Newton's third law]].<ref> {{cite web |last=Goldberg |first=David |date=17 November 2010 |title=What's the matter with the Higgs boson? |website=io9.com |url=http://io9.com/5690248/whats-the-matter-with-the-higgs-boson |access-date=21 January 2013 |url-status=usurped |archive-url=https://web.archive.org/web/20130121045610/http://io9.com/5690248/whats-the-matter-with-the-higgs-boson |archive-date=21 January 2013 }} </ref>

The Higgs boson is commonly misunderstood as responsible for mass, rather than the Higgs field, and as relating to most mass in the universe.<ref>{{Cite news |last=Brooks |first=Michael |author-link=Michael Brooks (science writer) |date=October 31, 2012 |title=Exploding the myths about the Higgs |url=https://www.newscientist.com/article/mg21628892-200-exploding-the-myths-about-the-higgs/ |url-status=live |archive-url=https://web.archive.org/web/20160413000339/https://www.newscientist.com/article/mg21628892-200-exploding-the-myths-about-the-higgs/ |archive-date=April 13, 2016 |access-date=July 6, 2024 |work=[[New Scientist]]}}</ref><ref>{{Cite news |last=Overbye |first=Dennis |author-link=Dennis Overbye |date=December 11, 2011 |title=Physicists Anxiously Await New Data on 'God Particle' |url=https://www.nytimes.com/2011/12/12/science/physicists-anxiously-await-news-of-the-god-particle.html |access-date=July 6, 2024 |work=[[The New York Times]]}}</ref><ref>{{Cite web |last=Yeager |first=Ashley |date=November 13, 2012 |title=Top 5 Common Misconceptions About the Higgs Particle |url=https://today.duke.edu/2012/11/higgsmisconceptions |access-date=July 6, 2024 |website=[[Duke University]]}}</ref> About 91% of the proton mass is due to the quark and gluon fields and the QCD [[conformal anomaly]] rather than the Higgs interaction.<ref>{{cite journal |last1=Walker-Loud |first1=André |title=Dissecting the Mass of the Proton |url=https://physics.aps.org/articles/v11/118 |journal=Physical Review Letters |page=118 |language=en |doi=10.1103/PhysRevLett.121.212001 |date=19 November 2018 |volume=121 |issue=21 |pmid=30517795 |arxiv=1808.08677 }}</ref>

=== Recognition and awards === There was considerable discussion prior to late 2013 of how to allocate the credit if the Higgs boson is proven, made more pointed as a [[Nobel Prize in Physics|Nobel Prize]] had been expected, and the very wide basis of people entitled to consideration. These include a range of theoreticians who made the Higgs mechanism theory possible, the theoreticians of the 1964 PRL papers (including Higgs himself), the theoreticians who derived from these a working electroweak theory and the Standard Model itself, and also the experimentalists at CERN and other institutions who made possible the proof of the Higgs field and boson in reality. The Nobel Prize has a limit of three persons to share an award, and some possible winners are already prize holders for other work, or are deceased (the prize is only awarded to persons in their lifetime). Existing prizes for works relating to the Higgs field, boson, or mechanism include: * Nobel Prize in Physics (1979) – [[Sheldon Glashow|Glashow]], [[Abdus Salam|Salam]], and [[Steven Weinberg|Weinberg]], ''for contributions to the theory of the unified weak and electromagnetic interaction between elementary particles''<ref> {{cite press release |title=The Nobel Prize in Physics 1979 |website=official Nobel Prize website |url=https://www.nobelprize.org/nobel_prizes/physics/laureates/1979 |access-date=13 June 2017 |url-status=live |archive-url=https://web.archive.org/web/20170617094107/http://www.nobelprize.org/nobel_prizes/physics/laureates/1979/ |archive-date=17 June 2017 }} </ref> * Nobel Prize in Physics (1999) – [[Gerard 't Hooft|'t Hooft]] and [[Tini Veltman|Veltman]], ''for elucidating the quantum structure of electroweak interactions in physics''<ref> {{cite press release |title=The Nobel Prize in Physics 1999 |website=official Nobel Prize website |url=https://www.nobelprize.org/nobel_prizes/physics/laureates/1999 |access-date=13 June 2017 |url-status=live |archive-url=https://web.archive.org/web/20170616225008/http://www.nobelprize.org/nobel_prizes/physics/laureates/1999/ |archive-date=16 June 2017 }} </ref> * [[Sakurai Prize|J. J. Sakurai Prize for Theoretical Particle Physics]] (2010){{snd}}Hagen, Englert, Guralnik, Higgs, Brout, and Kibble, ''for elucidation of the properties of spontaneous symmetry breaking in four-dimensional relativistic gauge theory and of the mechanism for the consistent generation of vector boson masses''<ref name="sakuraiprize" /> (for the 1964 papers described [[#History|above]]) * [[Wolf Prize]] (2004){{snd}}Englert, Brout, and Higgs * [[Breakthrough Prize in Fundamental Physics|Special Breakthrough Prize in Fundamental Physics]] (2013){{snd}}[[Fabiola Gianotti]] and [[Peter Jenni]], spokespersons of the ATLAS Collaboration and Michel Della Negra, Tejinder Singh Virdee, Guido Tonelli, and Joseph Incandela spokespersons, past and present, of the CMS collaboration, "For [their] leadership role in the scientific endeavour that led to the discovery of the new Higgs-like particle by the ATLAS and CMS collaborations at CERN's Large Hadron Collider".<ref> {{cite web |title=Special Breakthrough Prize Laureates |year=2013 |website=breakthroughprize.org |url=https://breakthroughprize.org/Laureates/1/P4/Y2013 |archive-url=https://web.archive.org/web/20170115055046/https://breakthroughprize.org/Laureates/1/P4/Y2013 |archive-date=15 January 2017 }}</ref> * Nobel Prize in Physics (2013) – [[Peter Higgs]] and [[François Englert]], ''for the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles, and which recently was confirmed through the discovery of the predicted fundamental particle, by the ATLAS and CMS experiments at CERN's Large Hadron Collider''<ref> {{cite press release |title=2013 Nobel Prize in Physics |website=official Nobel Prize website |url=https://www.nobelprize.org/nobel_prizes/physics/laureates/2013/ |access-date=13 June 2017 |url-status=live |archive-url=https://web.archive.org/web/20170611150717/http://www.nobelprize.org/nobel_prizes/physics/laureates/2013/ |archive-date=11 June 2017 }} </ref> Englert's co-researcher [[Robert Brout]] had died in 2011 and the Nobel Prize is [[Nobel Prize#Posthumous nominations|not ordinarily given posthumously]].<ref> {{cite news |last=Overbye |first=Dennis |author-link=Dennis Overbye |date=8 October 2013 |title=For Nobel, they can thank the 'god particle' |url=https://www.nytimes.com/2013/10/09/science/englert-and-higgs-win-nobel-physics-prize.html?_r=3& |url-status=live |archive-url=https://web.archive.org/web/20170630111148/http://www.nytimes.com/2013/10/09/science/englert-and-higgs-win-nobel-physics-prize.html?_r=3& |archive-date=30 June 2017 |access-date=3 November 2013 |newspaper=[[The New York Times]]}} </ref>

Additionally ''[[Physical Review Letters]]'' 50-year review (2008) recognised the [[1964 PRL symmetry breaking papers]] and Weinberg's 1967 paper ''A model of Leptons'' (the most cited paper in particle physics, as of 2012) "milestone Letters".<ref name="PRL_50years" />

Following reported observation of the Higgs-like particle in July 2012, several [[Indian media]] outlets reported on the supposed neglect of credit to Indian physicist [[Satyendra Nath Bose]] after whose work in the 1920s the class of particles "[[bosons]]" is named<ref name=AP-20120710> {{cite news |last=Daigle |first=Katy |date=10 July 2012 |title=India: Enough about Higgs, let's discuss the boson |newspaper=[[AP News]] |url=http://apnews.excite.com/article/20120710/D9VU1DRG0.html |access-date=10 July 2012 |archive-url=https://web.archive.org/web/20120923000409/http://apnews.excite.com/article/20120710/D9VU1DRG0.html |archive-date=23 September 2012 }} </ref><ref name=NYT-20120919> {{cite news |last=Bal |first=Hartosh Singh |author-link=Hartosh Singh Bal |date=19 September 2012 |title=The Bose in the Boson |url=http://latitude.blogs.nytimes.com/2012/09/19/indians-clamor-for-credit-for-the-bose-in-boson/ |newspaper=[[The New York Times]] |access-date=21 September 2012 |url-status=live |archive-url=https://web.archive.org/web/20191229062547/https://latitude.blogs.nytimes.com/2012/09/19/indians-clamor-for-credit-for-the-bose-in-boson/ |archive-date=29 December 2019 }} </ref> (although physicists have described Bose's connection to the discovery as tenuous).<ref name=outlook-in-bose> {{cite news |last=Alikhan |first=Anvar |date=16 July 2012 |title=The spark in a crowded field |newspaper=[[Outlook India]] |url=http://www.outlookindia.com/article.aspx?281539 |access-date=10 July 2012 |url-status=live |archive-url=https://web.archive.org/web/20120709141149/http://outlookindia.com/article.aspx?281539 |archive-date=9 July 2012 }} </ref>

== Technical aspects and mathematical formulation == {{See also|Mathematical formulation of the Standard Model}} [[File:Mecanismo de Higgs PH.png|thumb|The potential for the Higgs field, plotted as function of <math>\phi^0</math> and <math>\phi^3</math>. It has a ''sombrero'' or ''champagne-bottle profile'' at the ground.]] In the Standard Model, the Higgs field is a four-component scalar field that forms a complex [[doublet (physics)|doublet]] of the [[weak isospin]] SU(2) symmetry: : <math> \phi = \frac{1}{\sqrt{2}} \left( \begin{array}{c} \phi^1 + i\phi^2 \\ \phi^0 + i \phi^3 \end{array} \right)\, </math> while the field has charge +{{sfrac|1|2}} under the [[weak hypercharge]] U(1) symmetry.<ref name="PeskinSchroederHiggs"/>

{{blockquote| Note: This article uses the scaling convention where the electric charge, {{mvar|Q}}, the [[weak isospin]], {{mvar|T}}3, and the weak hypercharge, {{mvar|Y}}W, are related by {{nowrap|{{mvar|Q}} {{=}} {{mvar|T}}3 + {{mvar|Y}}W.}} A [[Gell-Mann–Nishijima formula|different convention]] used in most [[Weak hypercharge|other Wikipedia articles]] is {{nowrap|{{mvar|Q}} {{=}} {{mvar|T}}3 + {{sfrac|1|2}}{{mvar|Y}}W}}.<ref> {{cite journal |last1=Nakano |first1=T. |last2=Nishijima |first2=N. |year=1953 |title=Charge independence for V-particles |journal=[[Progress of Theoretical Physics]] |volume=10 |issue=5 |page=581 |doi=10.1143/PTP.10.581 |doi-access=free |bibcode = 1953PThPh..10..581N }} </ref><ref> {{cite journal |last=Nishijima |first=K. |year=1955 |title=Charge independence theory of V-particles |journal=[[Progress of Theoretical Physics]] |volume=13 |issue=3 |pages=285–304 |doi=10.1143/PTP.13.285 |doi-access=free |bibcode = 1955PThPh..13..285N }} </ref><ref> {{cite journal |last=Gell-Mann |first=M. |author-link=Murray Gell-Mann |year=1956 |title=The interpretation of the new particles as displaced charged multiplets |journal=[[Il Nuovo Cimento]] |volume=4 |issue=S2 |pages=848–866 |doi=10.1007/BF02748000 |bibcode=1956NCim....4S.848G|s2cid=121017243 }} </ref> }}

The Higgs part of the Lagrangian is<ref name="PeskinSchroederHiggs" /> : <math>\mathcal{L}_\text{H} = \left|\left(\partial_\mu - i g W_{\mu\,a} \tfrac{1}{2}\sigma^a - i\tfrac{1}{2} g' B_\mu\right)\phi\right|^2 + \mu_\text{H}^2 \phi^\dagger\phi - \lambda \left(\phi^\dagger\phi\right)^2\ ,</math> where <math>W_{\mu\,a}</math> and <math>B_\mu</math> are the [[gauge boson]]s of the SU(2) and U(1) symmetries, <math>g</math> and <math>g'</math> their respective [[coupling constant]]s, <math>\sigma^a</math> are the [[Pauli matrices]] (a complete set of generators of the SU(2) symmetry), and <math>\lambda > 0</math> and <math>\mu^{2}_\text{H} > 0</math>, so that the [[ground state]] breaks the SU(2) symmetry (see figure).

The ground state of the Higgs field (the bottom of the potential) is degenerate with different ground states related to each other by a SU(2) gauge transformation. It is always possible to [[unitarity gauge|pick a gauge]] such that in the ground state <math>\phi^1 = \phi^2 = \phi^3 = 0</math>. The expectation value of <math>\phi^0</math> in the ground state (the [[vacuum expectation value]] or VEV) is then <math>\left\langle\phi^0\right\rangle = \tfrac{1}{\sqrt{2\,}} v</math>, where <math>v = \tfrac{1}{\sqrt{\lambda \,}} \left|\mu_\text{H}\right|</math>. The measured value of this parameter is ~{{val|246|u=GeV/c2}}.<ref name="PDGreview2012"/> It has units of mass, and is the only free parameter of the Standard Model that is not a dimensionless number. Quadratic terms in <math>W_{\mu}</math> and <math>B_{\mu}</math> arise, which give masses to the W and Z bosons:<ref name="PeskinSchroederHiggs">{{harvnb|Peskin|Schroeder|1995|loc=Chapter 20}}</ref> : <math>\begin{align} m_\text{W} &= \tfrac{1}{2} v \left|\,g\,\right|\ , \\ m_\text{Z} &= \tfrac{1}{2} v \sqrt{ g^2 + {g'}^2\ }\ , \end{align}</math> with their ratio determining the [[Weinberg angle]], <math display="inline">\cos \theta_\text{W} = \frac{m_\text{W}}{\ m_\text{Z}\ } = \frac{\left|\,g\,\right|}{\ \sqrt{g^2 + {g'}^2\ }\ }</math>, and leave a massless U(1) [[photon]], <math>\gamma</math>. The mass of the Higgs boson itself is given by : <math>m_\text{H} = \sqrt{2 \mu^2_\text{H}\ } \equiv \sqrt{ 2 \lambda v^2\ }.</math>

The quarks and the leptons interact with the Higgs field through [[Yukawa interaction]] terms: : <math>\begin{align}\mathcal{L}_\text{Y} = &- \lambda_u^{i\,j}\frac{\ \phi^0 - i\phi^3\ }{\sqrt{2\ }}\overline u^i_\text{L} u^j_\text{R} + \lambda_u^{i\,j}\frac{\ \phi^1 - i\phi^2\ }{\sqrt{2\ }}\overline d^i_\text{L} u^j_\text{R}\\ &-\lambda_d^{i\,j}\frac{\ \phi^0 + i\phi^3\ }{\sqrt{2\ }}\overline d^i_\text{L} d^j_\text{R} - \lambda_d^{i\,j}\frac{\ \phi^1 + i\phi^2\ }{\sqrt{2\ }}\overline u^i_\text{L} d^j_\text{R}\\ &- \lambda_e^{i\,j}\frac{\ \phi^0 + i\phi^3\ }{\sqrt{2\ }}\overline e^i_\text{L} e^j_\text{R} - \lambda_e^{i\,j}\frac{\ \phi^1 + i\phi^2\ }{\sqrt{2\ }}\overline \nu^i_\text{L} e^j_\text{R} + \textrm{h.c.}\ ,\end{align}</math> where <math>(d,u,e,\nu)_\text{L,R}^i</math> are left-handed and right-handed quarks and leptons of the {{mvar|i}}th [[generation (physics)|generation]], <math>\lambda_\text{u,d,e}^{i\,j}</math> are matrices of Yukawa couplings where [[+ h.c.|h.c.]] denotes the hermitian conjugate of all the preceding terms. In the symmetry breaking ground state, only the terms containing <math>\phi^0</math> remain, giving rise to mass terms for the fermions. Rotating the quark and lepton fields to the basis where the matrices of Yukawa couplings are diagonal, one gets : <math>\mathcal{L}_\text{m} = -m_\text{u}^i \overline u^i_\text{L} u^i_\text{R} - m_\text{d}^i\overline d^i_\text{L} d^i_\text{R} - m_\text{e}^i\overline e^i_\text{L} e^i_\text{R} + \textrm{h.c.},</math> where the masses of the fermions are <math> m_\text{u,d,e}^i = \tfrac{1}{\sqrt{2\ }}\lambda_\text{u,d,e}^i v</math>, and <math> \lambda_\text{u,d,e}^i </math> denote the eigenvalues of the Yukawa matrices.<ref name="PeskinSchroederHiggs"/>

== See also == === Standard Model === {{cols}} * {{annotated link|Higgs mechanism}} * {{annotated link|History of quantum field theory}} * {{annotated link|Introduction to quantum mechanics}} * {{annotated link|Noncommutative standard model}} * {{annotated link|Noncommutative geometry}} * {{annotated link|Mathematical formulation of the Standard Model}} ** [[Mathematical formulation of the Standard Model#Quantum Field Theory|Standard Model fields overview]] ** [[Mathematical formulation of the Standard Model#Mass terms and the Higgs mechanism|mass terms and the Higgs mechanism]] * {{annotated link|Quantum gauge theory}} * {{annotated link|W and Z bosons}} {{colend}}

=== Other === {{cols}} * {{annotated link|Bose–Einstein statistics}} * [[Composite Higgs models]], an extension of the SM where the Higgs boson is made of smaller constituents * {{annotated link|Dalitz plot}} * ''[[Particle Fever]]'', a 2013 American documentary film following various LHC experiments and concluding with the identification of the Higgs boson * {{annotated link|Quantum triviality}} * {{annotated link|Scalar boson}} * {{annotated link|Stueckelberg action}} * {{annotated link|Tachyonic field}} * {{annotated link|ZZ diboson}} {{colend}}

== Explanatory notes == {{notelist|256em}}

== References == {{reflist|25em}}

== Sources == {{refbegin|25em|small=yes}} * {{cite journal |last=Bernstein |first=Jeremy |author-link=Jeremy Bernstein |date=January 1974 |title=Spontaneous symmetry breaking, gauge theories, the Higgs mechanism and all that |journal=Reviews of Modern Physics |volume=46 |issue=1 |pages=7–48 |bibcode=1974RvMP...46....7B |doi=10.1103/RevModPhys.46.7 |url=http://www.calstatela.edu/faculty/kaniol/p544/rmp46_p7_higgs_goldstone.pdf |access-date=10 December 2012 |archive-url=https://web.archive.org/web/20130121121537/http://www.calstatela.edu/faculty/kaniol/p544/rmp46_p7_higgs_goldstone.pdf |archive-date=21 January 2013 }} * {{cite book |last1=Peskin |first1=Michael E. |last2=Schroeder |first2=Daniel V. |year=1995 |title=An Introduction to Quantum Field Theory |publisher=Addison-Wesley Publishing Company |location=Reading, MA |isbn=978-0-201-50397-5 |url=https://archive.org/details/introductiontoqu0000pesk |url-access=registration }} * {{cite book |last1=Tipler |first1=Paul |last2=Llewellyn |first2=Ralph |year=2003 |title=Modern Physics |publisher=W. H. Freeman |isbn=978-0-7167-4345-3 }} * {{cite book |last=Griffiths |first=David |year=2008 |title=Introduction to Elementary Particles |edition=2nd revised |publisher=WILEY-VCH |isbn=978-3-527-40601-2 }} {{refend}}

== Further reading ==  {{refbegin|25em|small=yes}} * {{cite journal |first1=Yoichiro |last1=Nambu |author-link1=Yoichiro Nambu |first2=Giovanni |last2=Jona-Lasinio |author-link2=Giovanni Jona-Lasinio |year=1961 |title=Dynamical model of elementary particles based on an analogy with superconductivity |journal=[[Physical Review]] |volume=122 |issue=1 |pages=345–358 |doi=10.1103/PhysRev.122.345 |doi-access=free |bibcode = 1961PhRv..122..345N }} * {{cite journal |first=Philip W. |last=Anderson |author-link=Philip Warren Anderson |year=1963 |title=Plasmons, gauge invariance, and mass |journal=[[Physical Review]] |volume=130 |issue=1 |pages=439–442 |doi=10.1103/PhysRev.130.439 |bibcode = 1963PhRv..130..439A }} * {{cite journal |first1=Abraham |last1=Klein |author1-link=Abraham Klein (physicist) |first2=Benjamin W. |last2=Lee |author2-link=Benjamin W. Lee |year=1964 |title=Does spontaneous breakdown of symmetry imply zero-mass particles? |journal=[[Physical Review Letters]] |volume=12 |issue=10 |pages=266–268 |doi=10.1103/PhysRevLett.12.266 |bibcode=1964PhRvL..12..266K }} * {{cite journal |first=Walter |last=Gilbert |author-link=Walter Gilbert |year=1964 |title=Broken symmetries and massless particles |journal=[[Physical Review Letters]] |volume=12 |issue=25 |pages=713–714 |doi=10.1103/PhysRevLett.12.713 |bibcode=1964PhRvL..12..713G }} * {{cite journal |first=Peter |last=Higgs |author-link=Peter Higgs |title=Broken symmetries, massless particles and gauge fields |journal=[[Physics Letters]] |year=1964 |volume=12 |issue=2 |pages=132–133 |doi=10.1016/0031-9163(64)91136-9 |bibcode = 1964PhL....12..132H }} * {{cite book |first1=Gerald S. |last1=Guralnik |author-link1=Gerald Guralnik |first2=C.R. |last2=Hagen |author-link2=C. R. Hagen |first3=Tom W.B. |last3=Kibble |author-link3=Tom Kibble |year=1968 |chapter=Broken symmetries and the Goldstone theorem |pages=567–708 |editor1=[[Rodney L. Cool|Cool, R.L.]] |editor2=Marshak, R.E. |title=Advances in Physics |volume=2 |publisher=[[Interscience Publishers]] |isbn=978-0-470-17057-1 |chapter-url=http://www.datafilehost.com/download-7d512618.html |access-date=18 June 2011 |archive-url=https://web.archive.org/web/20120423102231/http://www.datafilehost.com/download-7d512618.html |archive-date=23 April 2012 }} * {{cite book |author=Carroll, Sean |year=2013 |title=The Particle at the End of the Universe: How the hunt for the Higgs boson leads us to the edge of a new world |publisher=Dutton |isbn=978-0-14-218030-3 }} * {{cite journal |first1=Karl |last1=Jakobs |first2=Chris |last2=Seez |year=2015 |title=The Higgs boson discovery |journal=[[Scholarpedia]] |volume=10 |issue=9 |article-number=32413 |doi=10.4249/scholarpedia.32413 |doi-access=free }} {{refend}}

== External links == {{Commons category}} {{Wiktionary}} {{wikiquote}}

=== Popular science, mass media, and general coverage === {{refbegin}} * [http://meroli.web.cern.ch/blog_higgs_animation.html Higgs Boson observation at CERN] {{Webarchive|url=https://web.archive.org/web/20191101225403/https://meroli.web.cern.ch/blog_higgs_animation.html |date=1 November 2019 }} * [http://cms.web.cern.ch/news/about-higgs-boson Hunting the Higgs Boson at C.M.S. Experiment, at CERN] * [http://www.exploratorium.edu/origins/cern/ideas/higgs.html The Higgs Boson] {{Webarchive|url=https://web.archive.org/web/20210317211905/http://www.exploratorium.edu/origins/cern/ideas/higgs.html |date=17 March 2021 }} by the CERN exploratorium. * [https://www.nytimes.com/2014/03/05/movies/particle-fever-tells-of-search-for-the-higgs-boson.html ''Particle Fever'', documentary film about the search for the Higgs Boson.] * [http://theatomsmashers.com/ ''The Atom Smashers'', documentary film about the search for the Higgs Boson at Fermilab.] * [https://www.theguardian.com/science/higgs-boson Collected Articles at the ''Guardian''] * [https://www.youtube.com/watch?v=vXZ-yzwlwMw Video (04:38)] – [[CERN]] Announcement on 4 July 2012, of the discovery of a particle which is suspected will be a Higgs Boson. * [http://vimeo.com/41038445 Video1 (07:44)] + [https://www.youtube.com/watch?v=0hn0jYjijNs Video2 (07:44)] – Higgs Boson Explained by CERN Physicist, [http://www.faculty.uci.edu/profile.cfm?faculty_id=5436 Dr. Daniel Whiteson] (16 June 2011). * [http://science.howstuffworks.com/higgs-boson.htm HowStuffWorks: What exactly is the Higgs Boson?] * {{cite web|last=Carroll|first=Sean|author-link=Sean M. Carroll|title=Higgs Boson with Sean Carroll|url=http://www.sixtysymbols.com/videos/higgs_sean.htm|website=Sixty Symbols|publisher=University of Nottingham}} * {{cite news|last=Overbye|first=Dennis|author-link=Dennis Overbye|title=Chasing the Higgs Boson: How 2 teams of rivals at CERN searched for physics' most elusive particle|url=https://www.nytimes.com/2013/03/05/science/chasing-the-higgs-boson-how-2-teams-of-rivals-at-CERN-searched-for-physics-most-elusive-particle.html|access-date=22 July 2013|newspaper=[[New York Times]] Science pages|date=5 March 2013}}{{snd}} ''New York Times'' "behind the scenes" style article on the Higgs search at ATLAS and CMS * The story of the Higgs theory by the authors of the PRL papers and others closely associated: ** {{cite web |last=Higgs |first=Peter |title=My Life as a Boson |url=http://www.kcl.ac.uk/nms/depts/physics/news/events/MyLifeasaBoson.pdf |publisher=Talk given at King's College, London, 24 November 2010 |year=2010 |access-date=17 January 2013 |archive-url=https://web.archive.org/web/20131104043410/http://www.kcl.ac.uk/nms/depts/physics/news/events/MyLifeasaBoson.pdf |archive-date=4 November 2013 }} (also: {{cite journal|doi=10.1142/S0217751X02013046|date=24 November 2010|title=My Life As a Boson: The Story of "the Higgs"|journal=International Journal of Modern Physics A|volume=17|pages=86–88|last1=Higgs|first1=Peter|issue=supp01 |bibcode=2002IJMPA..17S..86H}}) ** {{cite web|last=Kibble|first=Tom|title=Englert–Brout–Higgs–Guralnik–Hagen–Kibble mechanism (history)|url=http://www.scholarpedia.org/w/index.php?title=Englert–Brout–Higgs–Guralnik–Hagen–Kibble_mechanism_(history)&oldid=124215|publisher=Scholarpedia|access-date=17 January 2013|year=2009}} (also: {{cite journal|doi=10.4249/scholarpedia.8741|title=Englert-Brout-Higgs-Guralnik-Hagen-Kibble mechanism (history)|journal=Scholarpedia|volume=4|page=8741|year=2009|last1=Kibble|first1=Tom|issue=1|bibcode=2009SchpJ...4.8741K|doi-access=free}}) ** {{cite journal | first=Gerald| last=Guralnik | title=The History of the Guralnik, Hagen and Kibble development of the Theory of Spontaneous Symmetry Breaking and Gauge Particles | journal=[[International Journal of Modern Physics A]] | year=2009 | volume=24 | issue=14 | pages=2601–2627 | arxiv=0907.3466| bibcode=2009IJMPA..24.2601G | doi=10.1142/S0217751X09045431 | s2cid=16298371 }}, {{cite arXiv |first=Gerald| last=Guralnik |title=The Beginnings of Spontaneous Symmetry Breaking in Particle Physics. Proceedings of the DPF-2011 Conference, Providence, RI, 8–13 August 2011 |year=2011|eprint=1110.2253v1 |class=physics.hist-ph}}, and Guralnik, Gerald (2013). [http://www.sps.ch/en/articles/milestones_in_physics/heretical_ideas_that_provided_the_cornerstone_for_the_standard_model_of_particle_physics_1/ "Heretical Ideas that Provided the Cornerstone for the Standard Model of Particle Physics".] {{Webarchive|url=https://web.archive.org/web/20131015095448/http://www.sps.ch/en/articles/milestones_in_physics/heretical_ideas_that_provided_the_cornerstone_for_the_standard_model_of_particle_physics_1/ |date=15 October 2013 }} SPG Mitteilungen March 2013, No. 39, (p. 14), and [https://www.youtube.com/watch?v=WLZ78gwWQI0 Talk at Brown University about the 1964 PRL papers] ** [https://web.archive.org/web/20131020072910/http://www.conferences.uiuc.edu/bcs50/PDF/Anderson.pdf Philip Anderson (not one of the PRL authors) on symmetry breaking in superconductivity and its migration into particle physics and the PRL papers] * [http://xkcd.com/812/ Cartoon about the search] * {{cite web|url=http://www.phdcomics.com/comics.php?f=1684|date=19 February 2014|access-date=25 February 2014|title=True Tales from the Road: The Higgs Boson Re-Explained|last=Cham|first=Jorge|website=[[Piled Higher and Deeper]]}} * [https://www.bbc.co.uk/programmes/p004y2b7 Higgs Boson], BBC Radio 4 discussion with Jim Al-Khalili, David Wark & Roger Cashmore (''In Our Time'', 18 November 2004) {{refend}}

=== Significant papers and other === {{refbegin}} * {{cite journal|doi=10.1016/j.physletb.2012.08.020|title=Observation of a new particle in the search for the Standard Model Higgs boson with the ATLAS detector at the LHC|journal=Physics Letters B|volume=716|issue=2012|pages=1–29|year=2012|last1=Aad|first1=G.|display-authors=0|bibcode=2012PhLB..716....1A|arxiv=1207.7214|s2cid=119169617}} * {{cite journal|doi=10.1016/j.physletb.2012.08.021|title=Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC|journal=Physics Letters B|volume=716|issue=2012|pages=30–61|year=2012|last1=Chatrchyan|first1=S.|display-authors=0|bibcode=2012PhLB..716...30C|arxiv=1207.7235}} * [http://pdg.lbl.gov/2012/listings/rpp2012-list-higgs-boson.pdf Particle Data Group: Review of searches for Higgs Bosons.] * [https://books.google.com/books?id=ONhnbpq00xIC&pg=PA86 2001, a spacetime odyssey: proceedings of the Inaugural Conference of the Michigan Center for Theoretical Physics] : Michigan, 21–25 May 2001, (pp. 86–88), ed. Michael J. Duff, James T. Liu, {{ISBN|978-981-238-231-3}}, containing Higgs's story of the Higgs Boson. * {{cite journal |last1=Migdal |first1=A. A. |last2=Polyakov |first2=A. M. |year=1966 |title=Spontaneous Breakdown of Strong Interaction Symmetry and the Absence of Massless Particles |url=https://pdfs.semanticscholar.org/0865/a2bb7f85f8898e144c133b3d008ef9b96c0e.pdf |archive-url=https://web.archive.org/web/20180921225808/https://pdfs.semanticscholar.org/0865/a2bb7f85f8898e144c133b3d008ef9b96c0e.pdf |archive-date=21 September 2018 |journal=Soviet Physics JETP |volume=24 |issue=1 |page=91|bibcode=1967JETP...24...91M |s2cid=34510322 }}{{snd}} example of a 1966 Russian paper on the subject. * [https://www.energy.gov/science/doe-explainsthe-higgs-boson The Department of Energy Explains ... the Higgs Boson] {{refend}}

=== Introductions to the field === {{refbegin}} * [https://web.archive.org/web/20180901085224/http://www.quantumfieldtheory.info/Electroweak_Sym_breaking.pdf Electroweak Symmetry Breaking] – A pedagogic introduction to electroweak symmetry breaking with step by step derivations of many key relations, by Robert D. Klauber, 15 January 2018 (archived at Wayback Machine) * [https://web.archive.org/web/20130121121537/http://www.calstatela.edu/faculty/kaniol/p544/rmp46_p7_higgs_goldstone.pdf Spontaneous symmetry breaking, gauge theories, the Higgs mechanism and all that (Bernstein, ''Reviews of Modern Physics'' Jan 1974)]{{snd}} an introduction of 47 pages covering the development, history and mathematics of Higgs theories from around 1950 to 1974. {{refend}}

[[Category:2012 in science]] [[Category:Bosons]] [[Category:Electroweak theory]] [[Category:Elementary particles]] [[Category:Mass]] [[Category:Phase transitions]] [[Category:Standard Model]] [[Category:Quantum field theory]] [[Category:Subatomic particles with spin 0]] [[Category:Force carriers]]