Functional Renormalization Group Study of the Chiral Phase Transition Including Vector and Axial-vector Mesons

TL;DR

This study uses the functional renormalization group method on an extended Linear Sigma Model including vector and axial-vector mesons to analyze the chiral phase transition in QCD, revealing meson mass degeneracy and behavior near the transition.

Contribution

It introduces a FRG analysis of the eLSM with vector and axial-vector mesons, exploring effects of quark masses and axial anomaly on the chiral transition.

Findings

Degeneracy of chiral partner masses above transition temperature

Mass of $a_1$ meson decreases towards transition

Mass of $ ho$ meson increases towards transition

Abstract

The transition in quantum chromodynamics (QCD) from hadronic matter to the quark-gluon plasma (QGP) at high temperatures and/or net-baryon densities is associated with the restoration of chiral symmetry and can be investigated in the laboratory via heavy-ion collisions. We study this chiral transition within the functional renormalization group (FRG) approach applied to the two-flavor version of the extended Linear Sigma Model (eLSM). The eLSM is an effective model for the strong interaction and features besides scalar and pseudoscalar degrees of freedom also vector and axial- vector mesons. We discuss the impact of the quark masses and the axial anomaly on the order of the chiral transition. We also confirm the degeneracy of the masses of chiral partners above the transition temperature. We find that the mass of the $a_1$ meson ($\rho$ meson) decreases (increases) towards the chiral transition.