Chiral phase structure and critical end point in QCD

TL;DR

This paper investigates the phase structure of QCD at finite temperature and chemical potential using a self-consistent functional approach, providing insights into the chiral transition and the critical end point with improved theoretical methods.

Contribution

It introduces a novel self-consistent computation of quark-gluon vertex DSEs within a functional approach, enhancing the accuracy of QCD phase diagram predictions.

Findings

Results agree with lattice and FRG data at small densities

Quantitative agreement with FRG results at large densities

Accurate prediction of the critical end point location

Abstract

We map out the QCD phase structure at finite temperature and chemical potential for 2-flavour and 2 + 1-flavour QCD. This is done within a generalised functional approach to QCD put forward in arXiv:2002.07500 [hep-ph]. Specifically we compute the quark propagator and the finite-temperature and density fluctuations of the gluon propagator and the quark-gluon vertex on the basis of precision data for vacuum correlation functions. The novel ingredient is the direct self-consistent computation of the DSEs for the dressings of the quark-gluon vertex, in contrast to the common use of STI-inspired vertices. For small densities the results for the chiral order parameter agree with the respective lattice and functional renormalisation group results, for large densities the present results are in a quantitative agreement with the latter, including the location of the critical end point.