{{primary|date=August 2014}} The '''Dokshitzer–Gribov–Lipatov–Altarelli–Parisi''' ('''DGLAP''') '''evolution equations''' are equations in [[quantum chromodynamics]] (QCD) describing the variation of [[Parton distribution function|parton distribution functions]] with varying energy scales.<ref name=":0">{{Cite book|last=Thomson|first=Mark|title=Modern Particle Physics|date=2013|publisher=Cambridge University Press|isbn=978-1-107-03426-6|location=Cambridge, United Kingdom|at=§8.5.1 Scaling violations, pp. 201-202|chapter=|oclc=840462909}}</ref> Experimentally observed scaling violation in [[deep inelastic scattering]] is important evidence for the correctness of the equations and of QCD in general.<ref name=":0" /> The equations were first published in the western world by [[Guido Altarelli]] and [[Giorgio Parisi]] in 1977, and so are still sometimes called the '''Altarelli–Parisi equations'''.<ref>{{Cite journal |last1=Altarelli |first1=G. |last2=Parisi |first2=G. |date=1977-08-08 |title=Asymptotic freedom in parton language |url=https://dx.doi.org/10.1016%2F0550-3213%2877%2990384-4 |journal=Nuclear Physics B |language=en |volume=126 |issue=2 |pages=298–318 |doi=10.1016/0550-3213(77)90384-4 |bibcode=1977NuPhB.126..298A |issn=0550-3213|url-access=subscription }}</ref> Only later did it become known that an equivalent formula had been published in Russia by {{ill|Yuri Dokshitzer|lt=|de|Juri Lwowitsch Dokschizer}} in 1977,<ref>Yu. L. Dokshitzer. ''Sov. Phys. JETP'' 46:641 (1977).</ref> and by [[Vladimir Gribov]] and [[Lev Lipatov]] in 1972.<ref>V. N. Gribov, L. N. Lipatov. ''Sov. J. Nucl. Phys.'' 15:438 (1972).</ref>
The DGLAP QCD evolution equations are widely used in global determinations of [[Parton (particle physics)|parton]] distributions, like those from the Coordinated Theoretical-Experimental Project ([[Parton_(particle_physics)#Parton_distribution_functions|CTEQ]]) or [[NNPDF]] collaborations.{{Citation needed|date=November 2021}}
==See also== * [[Jet (particle physics)]] * [[HERA]] * [[APFEL (Software)]]
==References== {{Reflist}}
==Further reading== {{Cite journal|last=Martin|first=Alan D.|date=2008|title=Proton Structure, Partons, QCD, DGLAP and Beyond|url=https://www.actaphys.uj.edu.pl/fulltext?series=Reg&vol=39&page=2025|format=PDF|journal=[[Acta Physica Polonica B]]|volume=39|issue=9|pages=2025–2062|arxiv=0802.0161 |bibcode=2008AcPPB..39.2025M }}
==External links== * Guido Altarelli (2009) [http://www.scholarpedia.org/article/QCD_evolution_equations_for_parton_densities QCD evolution equations for parton densities]. Scholarpedia, 4(1):7124.
[[Category:Quantum chromodynamics]]
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