QCD phase diagram at finite baryon and isospin chemical potentials

TL;DR

This paper investigates the phase structure of two-flavor QCD at finite baryon and isospin chemical potentials using an extended PNJL model, revealing how the critical endpoint shifts with increasing isospin chemical potential.

Contribution

It introduces an extended PNJL model that accurately reproduces lattice QCD data across various chemical potentials, elucidating the phase diagram's structure and critical points.

Findings

Critical endpoint moves to a tricritical point with increasing mu_{iso}.

Thermodynamics at low T is governed by combined chiral and pion condensates.

Model reproduces lattice QCD data at different chemical potentials.

Abstract

The phase structure of two-flavor QCD is explored for thermal systems with finite baryon- and isospin-chemical potentials, mu_B and mu_{iso}, by using the Polyakov-loop extended Nambu--Jona-Lasinio (PNJL) model. The PNJL model with the scalar-type eight-quark interaction can reproduce lattice QCD data at not only mu_{iso}=mu_B=0 but also mu_{iso}>0 and mu_B=0. In the mu_{iso}-mu_{B}-T space, where T is temperature, the critical endpoint of the chiral phase transition in the mu_B-T plane at mu_{iso}=0 moves to the tricritical point of the pion-superfluidity phase transition in the mu_{iso}-T plane at mu_B=0 as mu_{iso} increases. The thermodynamics at small T is controlled by sqrt{sigma^2+pi^2} defined by the chiral and pion condensates, sigma and pi.