Aspects of chiral transition in a Hadron Resonance Gas model

Abstract

We study the chiral condensate for 2 + 1 flavor QCD with physical quarks within a non-interacting Hadron Resonance Gas (HRG) model. By including the latest information on the mass variation of the hadrons concerning the light quark mass, from lattice QCD and chiral perturbation theory, we show that it is possible to quite accurately account for the chiral crossover transition even within a conventional HRG model. We have calculated a pseudocritical temperature Tc=161.2±1.6 MeV and the curvature of crossover curve κ2=0.0203(7). These are in very good agreement with the latest continuum extrapolated results obtained from lattice QCD studies. We also discuss the limitations of extending such calculations toward the chiral limit. Furthermore, we study the effects of non-resonant hadron interactions within the HRG model and its consequences for the chiral transition in the regime of dense baryonic matter where lattice QCD results are not currently available.