A finite-density transition line for QCD with 695 MeV dynamical fermions

TL;DR

This study derives a phase transition line in the temperature-chemical potential plane for SU(3) gauge theory with 695 MeV fermions, revealing a high-temperature endpoint and a second lower-temperature endpoint, using effective action and mean-field methods.

Contribution

It introduces a novel approach combining the relative weights method and mean-field analysis to map the finite-density phase transition line in QCD-like theories.

Findings

Identifies a transition line with two endpoints in the temperature-chemical potential plane.

Finds an endpoint at high temperature consistent with expectations.

Discovers a second endpoint at a lower temperature, suggesting complex phase structure.

Abstract

We apply the relative weights method to SU(3) gauge theory with staggered fermions of mass 695 MeV at a set of temperatures in the range $151 \le T \le 267$ MeV, to obtain an effective Polyakov line action at each temperature. We then apply a mean-field method to search for phase transitions in the effective theory at finite densities. The result is a transition line in the plane of temperature and chemical potential, with an endpoint at high temperature, as expected, but also a second endpoint at a lower temperature. We cannot rule out the possibilities that a transition line reappears at temperatures lower than the range investigated, or that the second endpoint is absent for light quarks.