Phase diagram from PNJL models

Abstract

Possible phase diagrams of QCD at finite temperature and baryon chemical potential are discussed from the point of view of the effective model study especially by means of the Polyakov-loop coupled Nambu-Jona-Lasinio (PNJL) model. Two crossovers associated with quark deconfinement and chiral restoration are located at the (nearly) same temperature as long as the baryon chemical potential is small, but they eventually result in distinct boundaries on the phase diagram with increasing baryon density, which characterizes a region surrounded by two boundary curves. Also, the chiral critical point and the isentropic trajectories around it are critically argued.

The QCD deconfinement transition for heavy quarks and all baryon chemical potentials

“…5 we show Z φ eff /Z eff as a function of λ for φ = 2π/3. Since our model has a weak first order transition several volumes cross at the transition point λ 0 = 0.18805 (2).…”

“…Popular approaches are based on models which share the chiral and/or the Z(3)-symmetry with QCD, such as PNJL models, Polyakov loop + quark meson models, sigma models etc. For recent discussions and references, see [2][3][4]. Other approaches start from QCD directly and employ Dyson-Schwinger [5] or functional renormalisation group methods [6], using particular truncations.…”

“…Note that this remains true even for large µ/T , as we shall see in Eq. (3.12) 2. We exploit this behaviour to find a simple parametric description of the critical line in terms of the parameters of the original QCD action.…”