New Insight about the Effective Restoration of U_A(1) Symmetry

TL;DR

This paper investigates the restoration of U_A(1) symmetry at high temperatures using a functional renormalization group approach combined with a Polyakov-loop quark-meson model, revealing it occurs at higher temperatures than chiral symmetry restoration.

Contribution

It introduces a temperature-dependent 't Hooft term within a combined FRG and Polyakov-loop quark-meson model to study U_A(1) symmetry restoration patterns.

Findings

U_A(1) symmetry restores at higher temperature than chiral symmetry.

The model calculates meson spectra and mixing angles across temperatures.

Pressure and entropy density are analyzed to understand symmetry restoration effects.

Abstract

The effective restoration of the U_{A}(1) symmetry is revisited by implementing the functional renormalization group approach combining with the 2+1 flavor Polyakov-loop quark-meson model. A temperature-dependent 't Hooft term is taken to imitate the restoration of the U_{A}(1) symmetry. Order parameters, meson spectrum and mixing angles, especially the pressure and the entropy density of the system are calculated to explore the effects of different U_{A}(1) symmetry restoration patterns. We show then that the temperature for the restoration of the U_{A}(1) symmetry is much higher than that for the chiral symmetry SU_{A}(3).