Lund string model

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In particle physics, the Lund string model is a phenomenological model of hadronization. [1] [2] [3] 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. [4] (Electromagnetic field lines do not stringify, but instead spread out, because the photon, carrier of the electromagnetic force, does not self-interact.)

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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. [5] 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. [5] In 1979, the model was able to describe gluon jet fragmentation by considering the force field to be similar to a massless relativistic string. [5] The model successfully predicted a specific asymmetry in the particles produced in electron–positron collisions, observed in 1980. [5]

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. [6] 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

References

  1. ↑ Ferreres-Solé, Silvia; Sjöstrand, Torbjörn (2018-11-28). "The space–time structure of hadronization in the Lund model". The European Physical Journal C. 78 (11): 983. arXiv: 1808.04619 . Bibcode:2018EPJC...78..983F. doi:10.1140/epjc/s10052-018-6459-8. ISSN   1434-6052. PMC   6394252 . PMID   30881217.
  2. ↑ Roman, Pasechnik; Michal, Šumbera (September 2021). "Different Faces of Confinement". Universe. 7 (9). doi: 10.3390/univer (inactive 25 August 2025). ISSN   2218-1997. Archived from the original on 2025-01-26.{{cite journal}}: CS1 maint: DOI inactive as of August 2025 (link)
  3. ↑ Assi, Benoît; Bierlich, Christan; Ilten, Philip; Menzo, Tony; Mrenna, Stephen; Szewc, Manuel; Wilkinson, Michael K.; Youssef, Ahmed; Zupan, Jure (2025-08-12), Post-hoc reweighting of hadron production in the Lund string model, arXiv: 2505.00142
  4. ↑ Andersson, Bo, ed. (1998), "The Lund gluon model, its kinematics and decay properties", The Lund Model, Cambridge Monographs on Particle Physics, Nuclear Physics and Cosmology, Cambridge: Cambridge University Press, pp. 269–301, doi:10.1017/CBO9780511524363.015, ISBN   978-0-511-52436-3 , retrieved 2025-08-24
  5. 1 2 3 4 Forkman, Bengt; Verdozzi, Kristina Holmin, eds. (2016). "The Lund model for high energy collisions" (PDF). Physics in Lund: in time and space. Lund University.
  6. ↑ "Rope Hadronization and Strange Particle Production" (PDF).
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