In medium properties of axion within a Polyakov loop enhanced Nambu-Jona-Lasinio model

TL;DR

This paper estimates axion properties like mass and self-coupling within the PNJL model at finite temperature and chemical potential, highlighting significant differences from NJL model results and correlations with QCD phase transitions.

Contribution

It introduces a comprehensive analysis of axion properties using the PNJL model, incorporating both deconfinement and chiral symmetry restoration effects, and compares with lattice QCD data.

Findings

Axion mass and self-coupling vary significantly near the QCD transition.

PNJL model results differ notably from NJL model calculations.

Axion properties are correlated with chiral and deconfinement transitions.

Abstract

We estimate the axion properties i.e. its mass, topological susceptibility and the self-coupling within the framework of Polyakov loop enhanced Nambu-Jona-Lasinio (PNJL) model at finite temperature and quark chemical potential. PNJL model, where quarks couple simultaneously to the chiral condensate and to a background temporal quantum chromodynamics (QCD) gauge field, includes two important features of QCD phase transition, i.e. deconfinement and chiral symmetry restoration. The Polyakov loop in PNJL model plays an important role near the critical temperature. We have shown significant difference in the axion properties calculated in PNJL model compared to the same obtained using Nambu-Jona-Lasinio (NJL) model. We find that both the mass of the axion and its self-coupling are correlated with the chiral transition as well as the confinement-deconfinement transition. We have also estimated the axion properties at finite chemical potential. Across the QCD transition temperature and/or quark chemical potential axion mass and its self-coupling also changes significantly. Since the PNJL model includes both the fermionic sector and the gauge fields, it can give reliable estimates of the axion properties, i.e. it's mass and the self-coupling in a hot and dense QCD medium. We also compare our results with the lattice QCD results whenever available.