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

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.

Comments: 11 pages, 9 figures. v2: references added, minor cosmetic changes, and a small numerical correction in the appendix. v3: significant revisions in procedure, figures added, some comparison with other results in the literature. v4: corrected one citation and minor misprint