{{Short description|Model of hadronization}}In particle physics, the '''Lund string model''' is a phenomenological model of hadronization.<ref>{{Cite journal |last1=Ferreres-Solé |first1=Silvia |last2=Sjöstrand |first2=Torbjörn |date=2018-11-28 |title=The space–time structure of hadronization in the Lund model |url=https://doi.org/10.1140/epjc/s10052-018-6459-8 |journal=The European Physical Journal C |language=en |volume=78 |issue=11 |pages=983 |doi=10.1140/epjc/s10052-018-6459-8 |doi-access=free|issn=1434-6052 |pmc=6394252 |pmid=30881217 |arxiv=1808.04619 |bibcode=2018EPJC...78..983F }}</ref><ref>{{Cite journal |last1=Roman |first1=Pasechnik |last2=Michal |first2=Šumbera |date=September 2021 |title=Different Faces of Confinement |url=https://www.mdpi.com/2218-1997/7/9/330 |journal=Universe |language=en |volume=7 |issue=9 |doi=10.3390/univer |doi-broken-date=25 August 2025 |doi-access=free |issn=2218-1997 |archive-url=https://web.archive.org/web/20250126165613/https://www.mdpi.com/2218-1997/7/9/330 |archive-date=2025-01-26 |access-date=2025-08-24 |url-status=live }}</ref><ref>{{Citation |last1=Assi |first1=Benoît |title=Post-hoc reweighting of hadron production in the Lund string model |date=2025-08-12 |arxiv=2505.00142 |last2=Bierlich |first2=Christan |last3=Ilten |first3=Philip |last4=Menzo |first4=Tony |last5=Mrenna |first5=Stephen |last6=Szewc |first6=Manuel |last7=Wilkinson |first7=Michael K. |last8=Youssef |first8=Ahmed |last9=Zupan |first9=Jure |journal=SciPost Physics |volume=19 |issue=4 |article-number=104 |doi=10.21468/SciPostPhys.19.4.104 |doi-access=free }}</ref> It treats all but the highest-energy gluons as field lines, which are attracted to each other due to the gluon self-interaction and so form a narrow tube (or string) of strong color field.<ref>{{Citation |title=The Lund gluon model, its kinematics and decay properties |date=1998 |work=The Lund Model |pages=269–301 |editor-last=Andersson |editor-first=Bo |url=https://www.cambridge.org/core/books/lund-model/lund-gluon-model-its-kinematics-and-decay-properties/53CB0B7E775606EB794730C494784B97 |access-date=2025-08-24 |series=Cambridge Monographs on Particle Physics, Nuclear Physics and Cosmology |place=Cambridge |publisher=Cambridge University Press |doi=10.1017/CBO9780511524363.015 |isbn=978-0-511-52436-3}}</ref> (Electromagnetic field lines do not stringify, but instead spread out, because the photon, carrier of the electromagnetic force, does not self-interact.)
The model is named after the particle theory group of Lund University, which developed it. It was derived from the 1977 PhD thesis of Carsten Peterson, supervised by Bo Andersson and Gösta Gustafson.<ref name=":0">{{Cite book |title=Physics in Lund: in time and space |date=2016 |publisher=Lund University |editor-last=Forkman |editor-first=Bengt |chapter=The Lund model for high energy collisions |editor-last2=Verdozzi |editor-first2=Kristina Holmin |chapter-url=http://history.fysik.lu.se/EN/EN_Bok_17_LB_web.pdf}}</ref> The model was refined by the contributions of researchers of the group, like Torbjörn Sjöstrand, Bo Söderberg, Gunnar Ingelman, Hans-Uno Bengtsson, and Ulf Pettersson.<ref name=":0" /> In 1979, the model was able to describe gluon jet fragmentation by considering the force field to be similar to a massless relativistic string.<ref name=":0" /> The model successfully predicted a specific asymmetry in the particles produced in electron–positron collisions, observed in 1980.<ref name=":0" />
String fragmentation is one of the parton fragmentation models used in the PYTHIA/Jetset and the University of California, Los Angeles as event generators, and explains many features of hadronization quite well.<ref>{{Cite web |title=Rope Hadronization and Strange Particle Production |url=https://indico.cern.ch/event/576735/papers/2565832/files/5808-template.pdf}}</ref> In particular, the model predicts that in addition to the particle jets formed along the original paths of two separating quarks, there will be a spray of hadrons produced between the jets by the string itself—which is precisely what is observed.
==See also== *QCD string *Color confinement
== References == {{Ref-list}}
== External links == *[https://www.cambridge.org/core/books/lund-model/ADFC4799240BF3CC16E8E0991EB87674 The Lund Model by Bo Andersson]
Category:Quantum chromodynamics Category:Experimental particle physics