Melting and freeze-out conditions of hadrons in a thermal medium

Juan M Torres-Rincon,Jean-Bernard Rose,Joseph Tindall,Joerg Aichelin,Hannah Petersen

doi:10.1051/epjconf/201817114007

Abstract

We describe two independent frameworks which provide unambiguous determinations of the deconfinement and the decoupling conditions of a relativistic gas at finite temperature. First, we use the Polyakov-Nambu-Jona–Lasinio model to compute meson and baryon masses at finite temperature and determine their melting temperature as a function of their strangeness content. Second, we analyze a simple expanding gas within a Friedmann-Robertson-Walker metric, which admits a well-defined decoupling mechanism. We examine the decoupling time as a function of the particle mass and cross section. We find evidences of an inherent dependence of the hadronization and freeze-out conditions on flavor, and on mass and cross section, respectively.

Highlights

Statistical thermal models [1] have been very successful in characterizing the thermodynamical properties of the hadronic medium created in heavy-ion collisions at the chemical freeze-out
We describe two independent frameworks which provide unambiguous determinations of the deconfinement and the decoupling conditions of a relativistic gas at finite temperature
We examine the decoupling time as a function of the particle mass and cross section

Summary

Introduction

Statistical thermal models [1] have been very successful in characterizing the thermodynamical properties of the hadronic medium created in heavy-ion collisions at the chemical freeze-out. The Ξ and Ω baryons seems to prefer a larger freeze-out temperature (with a difference of ∼16 MeV) than the T f for protons. There exist indications of a flavor hierarchy in (at least) two different observables: the QCD phase transition and the freeze-out temperatures [4]. This issue have created much interest at this SQM2017 conference, e.g. © The Authors, published by EDP Sciences. The freeze-out temperature will be represented by the decoupling temperature of an expanding system of particles using a relativistic transport model

Melting temperature hierarchy in the PNJL model

Baryon p ρ

Expanding system and its decoupling

Conclusion