A perturbative study of the QCD phase diagram for heavy quarks at nonzero chemical potential: two-loop corrections

TL;DR

This paper enhances the understanding of the QCD phase diagram for heavy quarks at finite chemical potential by incorporating two-loop corrections into a background field approach, improving agreement with lattice data and analyzing thermodynamic properties.

Contribution

It introduces two-loop corrections to the background field effective potential in QCD, providing a more accurate perturbative description of the phase diagram for heavy quarks at nonzero chemical potential.

Findings

Two-loop corrections improve agreement with lattice results.

The equation of state and thermodynamic stability are analyzed at two-loop order.

Polyakov loop behavior aligns with quark and anti-quark free energies.

Abstract

We extend a previous investigation of the QCD phase diagram with heavy quarks in the context of background field methods by including the two-loop corrections to the background field effective potential. The nonperturbative dynamics in the pure-gauge sector is modeled by a phenomenological gluon mass term in the Landau-DeWitt gauge-fixed action, which results in an improved perturbative expansion. We investigate the phase diagram at nonzero temperature and (real or imaginary) chemical potential. Two-loop corrections yield an improved agreement with lattice data as compared to the leading-order results. We also compare with the results of nonperturbative approaches. We further study the equation of state as well as the thermodynamic stability of the system at two-loop order. Finally, we show, using simple thermodynamic arguments, that the behavior of the Polyakov loops as functions of the chemical potential complies with their interpretation in terms of quark and anti-quark free energies.