The effective QCD phase diagram and the critical end point

TL;DR

This paper models the QCD phase diagram using the linear sigma model with quarks, locating the critical end point and emphasizing the importance of plasma screening effects and chiral symmetry breaking in determining phase transition features.

Contribution

It provides a novel calculation of the QCD critical end point using the linear sigma model, incorporating plasma screening effects and linking the CEP location to chiral symmetry restoration.

Findings

Critical end point located at (1.2, 0.8) in scaled units.

CEP location consistent with lattice-inspired calculations.

Plasma screening effects are crucial for accurate phase diagram modeling.

Abstract

We study the QCD phase diagram on the plane of temperature T and quark chemical potential mu, modelling the strong interactions with the linear sigma model coupled to quarks. The phase transition line is found from the effective potential at finite T and mu taking into accounts the plasma screening effects. We find the location of the critical end point (CEP) to be (mu^CEP/T_c,T^CEP/T_c) sim (1.2,0.8), where T_c is the (pseudo)critical temperature for the crossover phase transition at vanishing mu. This location lies within the region found by lattice inspired calculations. The results show that in the linear sigma model, the CEP's location in the phase diagram is expectedly determined solely through chiral symmetry breaking. The same is likely to be true for all other models which do not exhibit confinement, provided the proper treatment of the plasma infrared properties for the description of chiral symmetry restoration is implemented. Similarly, we also expect these corrections to be substantially relevant in the QCD phase diagram.