Strong-coupling lattice study for QCD phase diagram including both chiral and deconfinement dynamics

TL;DR

This paper develops an analytic framework for the QCD phase diagram using strong-coupling lattice QCD, capturing both chiral and deconfinement transitions at finite temperature and chemical potential.

Contribution

It derives an effective potential including both chiral and deconfinement dynamics with finite coupling effects in mean-field approximation.

Findings

Polyakov loop shows two peaks as a function of temperature for small quark masses.

One peak is linked to chiral symmetry restoration, the other to deconfinement.

The deconfinement peak temperature is nearly independent of quark mass and chemical potential.

Abstract

We investigate the QCD phase diagram by using the strong-coupling expansion of the lattice QCD with one species of staggered fermion and the Polyakov loop effective action at finite temperature (T) and quark chemical potential (mu). We derive an analytic expression of effective potential Feff including both the chiral (U(1)) and the deconfinement (Z_Nc) dynamics with finite coupling effects in the mean-field approximation. The Polyakov loop increasing rate (dl/dT) is found to have two peaks as a function of T for small quark masses. One of them is the chiral-induced peak associated with the rapid decrease of the chiral condensate. The temperature of the other peak is almost independent of the quark mass or chemical potential, and this peak is interpreted as the Z_Nc-induced peak.