Chiral phase transition: effective field theory and holography

TL;DR

This paper develops an effective field theory and holographic approach to study the second-order chiral phase transition in QCD matter at finite temperature, capturing fluctuations, dissipation, and symmetry breaking.

Contribution

It introduces a combined effective field theory and holographic Schwinger-Keldysh method for analyzing chiral phase transitions, confirming results with a modified AdS/QCD model.

Findings

Effective stochastic equations resemble model F dynamics.

The approach captures fluctuations and dissipation near the transition.

Discussion of chiral symmetry breaking and Goldstone modes.

Abstract

We consider the chiral phase transition relevant for QCD matter at finite temperature but with vanishing baryon density. Presumably, the chiral phase transition is of second order for two-flavor QCD in the chiral limit. Near the transition temperature, we apply the Schwinger-Keldysh formalism and construct a low-energy effective field theory for the system, in which fluctuations and dissipations are systematically captured. The dynamical variables involve the chiral charge densities and order parameter (chiral condensate). Via the holographic Schwinger-Keldysh technique, the effective action is further confirmed within a modified AdS/QCD model. With higher-order terms suitably neglected, the stochastic equations derived from the effective field theory resemble those of model F in the Hohenberg-Halperin classification. Within the effective field theory, we briefly discuss the spontaneous breaking of chiral symmetry and Goldstone modes.