Dressed Polyakov loop and flavor dependent phase transitions

Abstract

The chiral condensate and dressed Polyakov loop at finite temperature and density have been investigated in the framework of the ${N}_{f}=2+1$ Nambu-Jona-Lasinio (NJL) model with two degenerate $u$, $d$ quarks and one strange quark. In the case of explicit chiral symmetry breaking with physical quark masses, it is found that the phase transitions for light $u$, $d$, and $s$ quark are sequentially happened, and the separation between the transition lines for different flavors becomes wider and wider with the increase of baryon density. For each flavor, the pseudocritical temperatures for chiral condensate and dressed Polyakov loop differ in a narrow transition range in the lower baryon density region, and the two transitions coincide in the higher baryon density region.