On finite-temperature holographic QCD in the Veneziano limit

TL;DR

This paper explores finite-temperature holographic models of QCD in the Veneziano limit, analyzing phase transitions, chiral symmetry, and thermodynamic properties across different flavor ratios, revealing critical behavior and conformal crossover phenomena.

Contribution

It provides a detailed phase diagram and thermodynamic analysis of holographic QCD models at finite temperature in the Veneziano limit, including the identification of critical points and Miransky scaling.

Findings

First order chiral symmetry breaking transition for x_f up to x_c

Continuous crossover between conformal phases for x_f between x_c and 11/2

Approach to critical x_c exhibits Miransky scaling

Abstract

Holographic models in the T=0 universality class of QCD in the limit of large number N_c of colors and N_f massless fermion flavors, but constant ratio x_f=N_f/N_c, are analyzed at finite temperature. The models contain a 5-dimensional metric and two scalars, a dilaton sourcing TrF^2 and a tachyon dual to \bar qq. The phase structure on the T,x_f plane is computed and various 1st order, 2nd order transitions and crossovers with their chiral symmetry properties are identified. For each x_f, the temperature dependence of p/T^4 and the quark-antiquark -condensate is computed. In the simplest case, we find that for x_f up to the critical x_c\sim 4 there is a 1st order transition on which chiral symmetry is broken and the energy density jumps. In the conformal window x_c<x_f<11/2, there is only a continuous crossover between two conformal phases. When approaching x_c from below, x_f\to x_c, temperature scales approach zero as specified by Miransky scaling.