Analytic Study on Chiral Phase Transition in Holographic QCD

TL;DR

This paper analytically investigates chiral symmetry breaking in holographic QCD, revealing how black hole phase transitions influence the nature of chiral phase transitions across different chemical potentials.

Contribution

It provides an analytical calculation of quark condensation in a holographic QCD model, linking black hole phase transitions to chiral symmetry breaking behavior.

Findings

At small chemical potential, chiral symmetry breaking is a crossover.

At large chemical potential, the transition becomes first order.

The phase diagram aligns qualitatively with lattice QCD and NJL model results.

Abstract

The chiral symmetry breaking ($\chi_{SB}$) is one of the most fundamental problems in QCD. In this paper, we calculate quark condensation analytically in a holographic QCD model dual to the Einstein-Maxwell-Dilaton (EMD) system coupled to a probe scalar field. We find that the black hole phase transition in the EMD system seriously affects $\chi_{SB}$. At small chemical potential, $\chi_{SB}$ behaves as a crossover. For large chemical potential $\mu>\mu_c$, $\chi_{SB}$ becomes first order with exactly the same transition temperature as the black hole phase transition by a bypass mechanism. The phase diagram we obtained is qualitatively consistent with the recent results from lattice QCD simulations and NJL models.