The phase diagram of QCD with four degenerate quarks

TL;DR

This paper investigates the phase diagram of QCD with four degenerate quarks at finite temperature and density, using analytic continuation and Monte Carlo simulations to improve understanding of the pseudo-critical line's behavior.

Contribution

It introduces a high-statistics Monte Carlo approach to determine pseudo-critical couplings at imaginary chemical potentials, revealing deviations from quadratic dependence and refining extrapolations to real chemical potential.

Findings

Deviations from quadratic dependence on chemical potential.

High-statistics Monte Carlo results for pseudo-critical couplings.

Implications for the shape of the QCD phase diagram at real chemical potential.

Abstract

We revisit the determination of the pseudo-critical line of QCD with four degenerate quarks at non-zero temperature and baryon density by the method of analytic continuation. We determine the pseudo-critical couplings at imaginary chemical potentials by high-statistics Monte Carlo simulations and reveal deviations from the simple quadratic dependence on the chemical potential visible in earlier works on the same subject. Finally, we discuss the implications of our findings for the shape of the pseudo-critical line at real chemical potential, comparing different possible extrapolations.