2+1 Flavor Polyakov--Nambu--Jona-Lasinio Model at Finite Temperature and Nonzero Chemical Potential

TL;DR

This paper extends the PNJL model to 2+1 flavors to analyze chiral and deconfinement transitions at finite temperature and chemical potential, aligning with lattice QCD results and predicting the phase diagram and critical endpoint behavior.

Contribution

The study develops a 2+1 flavor PNJL model to explore phase transitions, incorporating flavor mixing effects and providing predictions for the phase diagram at finite temperature and chemical potential.

Findings

Strange quark number susceptibility shows an inflection point at deconfinement.

The phase diagram features a critical endpoint that moves with flavor-mixing strength.

Model results agree with lattice QCD simulations.

Abstract

We extend the Polyakov-loop improved Nambu--Jona-Lasinio (PNJL) model to 2+1 flavor case to study the chiral and deconfinement transitions of strongly interacting matter at finite temperature and nonzero chemical potential. The Polyakov-loop, the chiral susceptibility of light quarks (u and d) and the strange quark number susceptibility as functions of temperature at zero chemical potential are determined and compared with the recent results of Lattice QCD simulations. We find that there is always an inflection point in the curve of strange quark number susceptibility accompanying the appearance of the deconfinement phase, which is consistent with the result of Lattice QCD simulations. Predictions for the case at nonzero chemical potential and finite temperature are made as well. We give the phase diagram in terms of the chemical potential and temperature and find that the critical endpoint (CEP) moves down to low temperature and finally disappears with the decrease of the strength of the 't Hooft flavor-mixing interaction.