Chiral phase transition of QCD with Nf = 2 + 1 flavors from holography

Abstract

Chiral phase transition for three-flavor Nf = 2 + 1 QCD with mu = md ≠ ms is investigated in a modified soft-wall holographic QCD model. Solving temperature dependent chiral condensates from equations of motion of the modified soft-wall model, we extract the quark mass dependence of the order of chiral phase transition in the case of Nf = 2 + 1, and the result is in agreement with the “Columbia Plot”, which is summarized from lattice simulations and other non-perturbative methods. First order phase transition is observed around the three flavor chiral limit mu/d = 0, ms = 0, while at sufficient large quark masses it turns to be a crossover phase transition. The first order and crossover regions are separated by a second order phase transition line. The second order line is divided into two parts by the mu/d = ms line, and the ms dependence of the transition temperature in these two parts are totally contrast, which might indicate that the two parts are governed by different universality classes.