Journal of High Energy Physics

, 2017:140 | Cite as

Thermodynamical string fragmentation

  • Nadine Fischer
  • Torbjörn Sjöstrand
Open Access
Regular Article - Theoretical Physics


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.


Phenomenological Models QCD Phenomenology 


Open Access

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© The Author(s) 2017

Authors and Affiliations

  1. 1.Theoretical Particle Physics, Department of Astronomy and Theoretical PhysicsLund UniversityLundSweden
  2. 2.School of Physics and AstronomyMonash UniversityClaytonAustralia

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