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Thermodynamical string fragmentation

Fischer, Nadine LU and Sjöstrand, Torbjörn LU (2017) In Journal of High Energy Physics 2017(1).
Abstract

The observation of heavy-ion-like behaviour in pp collisions at the LHC suggests that more physics mechanisms are at play than traditionally assumed. The introduction e.g. of quark-gluon plasma or colour rope formation can describe several of the observations, but as of yet there is no established paradigm. In this article we study a few possible modifications to the Pythia event generator, which describes a wealth of data but fails for a number of recent observations. Firstly, we present a new model for generating the transverse momentum of hadrons during the string fragmentation process, inspired by thermodynamics, where heavier hadrons naturally are suppressed in rate but obtain a higher average transverse momentum. Secondly,... (More)

The observation of heavy-ion-like behaviour in pp collisions at the LHC suggests that more physics mechanisms are at play than traditionally assumed. The introduction e.g. of quark-gluon plasma or colour rope formation can describe several of the observations, but as of yet there is no established paradigm. In this article we study a few possible modifications to the Pythia event generator, which describes a wealth of data but fails for a number of recent observations. Firstly, we present a new model for generating the transverse momentum of hadrons during the string fragmentation process, inspired by thermodynamics, where heavier hadrons naturally are suppressed in rate but obtain a higher average transverse momentum. Secondly, close-packing of strings is taken into account by making the temperature or string tension environment-dependent. Thirdly, a simple model for hadron rescattering is added. The effect of these modifications is studied, individually and taken together, and compared with data mainly from the LHC. While some improvements can be noted, it turns out to be nontrivial to obtain effects as big as required, and further work is called for.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Phenomenological Models, QCD Phenomenology
in
Journal of High Energy Physics
volume
2017
issue
1
publisher
Springer
external identifiers
  • scopus:85011601778
  • wos:000397645900003
ISSN
1126-6708
DOI
10.1007/JHEP01(2017)140
language
English
LU publication?
yes
id
a70029f5-7612-4bf8-9aec-aeb5f9e0d37e
date added to LUP
2017-02-16 07:20:49
date last changed
2018-06-24 05:10:23
@article{a70029f5-7612-4bf8-9aec-aeb5f9e0d37e,
  abstract     = {<p>The observation of heavy-ion-like behaviour in pp collisions at the LHC suggests that more physics mechanisms are at play than traditionally assumed. The introduction e.g. of quark-gluon plasma or colour rope formation can describe several of the observations, but as of yet there is no established paradigm. In this article we study a few possible modifications to the Pythia event generator, which describes a wealth of data but fails for a number of recent observations. Firstly, we present a new model for generating the transverse momentum of hadrons during the string fragmentation process, inspired by thermodynamics, where heavier hadrons naturally are suppressed in rate but obtain a higher average transverse momentum. Secondly, close-packing of strings is taken into account by making the temperature or string tension environment-dependent. Thirdly, a simple model for hadron rescattering is added. The effect of these modifications is studied, individually and taken together, and compared with data mainly from the LHC. While some improvements can be noted, it turns out to be nontrivial to obtain effects as big as required, and further work is called for.</p>},
  articleno    = {140},
  author       = {Fischer, Nadine and Sjöstrand, Torbjörn},
  issn         = {1126-6708},
  keyword      = {Phenomenological Models,QCD Phenomenology},
  language     = {eng},
  month        = {01},
  number       = {1},
  publisher    = {Springer},
  series       = {Journal of High Energy Physics},
  title        = {Thermodynamical string fragmentation},
  url          = {http://dx.doi.org/10.1007/JHEP01(2017)140},
  volume       = {2017},
  year         = {2017},
}