Realization of chiral symmetry breaking and restoration in holographic QCD

TL;DR

This paper successfully models chiral symmetry breaking and restoration in holographic QCD, capturing phase transitions at finite temperature with proper scalar and dilaton profiles, enhancing the framework's non-perturbative QCD applications.

Contribution

It introduces a novel holographic QCD setup that accurately reproduces chiral phase transitions, including their order and dependence on quark masses.

Findings

Chiral condensate decreases with temperature in the vacuum.

Second-order transition for two flavors in the chiral limit.

First-order transition for three flavors in the chiral limit.

Abstract

With proper profiles of the scalar potential and the dilaton field, for the first time, the spontaneous chiral symmetry breaking in the vacuum and its restoration at finite temperature are correctly realized in the holographic QCD framework. In the chiral limit, a nonzero chiral condensate develops in the vacuum and decreases with temperature, and the phase transition is of 2nd order for two-flavor case and of 1st order for three-flavor case. In the case of explicit chiral symmetry breaking, in two-flavor case, the 2nd order phase transition turns to crossover with any nonzero current quark mass, and in three-flavor case, the 1st order phase transition turns to crossover at a finite current quark mass. The correct description of chiral symmetry breaking and restoration makes the holographic QCD models more powerful in dealing with non-perturbative QCD phenomena. This framework can be regarded as a general set up in application of AdS/CFT to describe conventional Ginzburg-Landau-Wilson type phase transitions, e.g. in condensed matter and cosmology systems.