The QCD phase diagram from Schwinger-Dyson Equations

TL;DR

This paper investigates the QCD phase diagram using Schwinger-Dyson equations, identifying a crossover, a critical point, and chiral symmetry restoration at finite temperature and chemical potential.

Contribution

It introduces a truncation method for SDEs matched with lattice results to explore the QCD phase diagram at finite chemical potential.

Findings

Identification of a crossover at low chemical potential

Detection of a critical point near mu ≈ 0.22 GeV

Chiral symmetry restoration at mu ≈ 0.53 GeV

Abstract

We study the phase diagram of quantum chromodynamics (QCD). For this purpose we employ the Schwinger-Dyson equations (SDEs) technique and construct a truncation of the infinite tower of equations by demanding a matching with the lattice results for the quark-anti-quark condensate at finite temperature (T), for zero quark chemical potential (mu), that is, the region where lattice calculations are expected to provide reliable results. We compute the evolution of the phase diagram away from T=0 for increasing values of the chemical potential by following the evolution of the heat capacity as a function of T and mu. The behavior of this thermodynamic variable clearly demonstrates the existence of a cross-over for mu less than a critical value. However, the heat capacity develops a singularity near mu approx 0.22 GeV marking the onslaught of a first order phase transition characterized by the existence of a critical point. The critical line continues until mu approx 0.53 GeV where Tc=0 and thus chiral symmetry is finally restored.