Does the chiral magnetic effect change the dynamic universality class in QCD?

TL;DR

This paper investigates whether the chiral magnetic effect alters the dynamic universality class of the chiral phase transition in QCD, finding it shifts to model A and that the CME transport coefficient remains unaffected by critical fluctuations.

Contribution

The study demonstrates that the chiral magnetic effect changes the dynamic universality class in QCD to model A using renormalization-group analysis.

Findings

CME changes the dynamic universality class to model A

CME transport coefficient is not renormalized by critical fluctuations

Critical dynamics near the chiral phase transition are characterized by the new universality class

Abstract

In QCD matter under an external magnetic field, the chiral magnetic effect (CME) leads to the collective gapless mode called the chiral magnetic wave (CMW). Since dynamic universality class generally depends on low-energy gapless modes, it is nontrivial whether the CME and the resulting CMW change that of the second-order chiral phase transition in QCD. To address this question, we study the critical dynamics near the chiral phase transition in massless two-flavor QCD under an external magnetic field. By performing the dynamic renormalization-group analysis within the epsilon expansion, we find that the presence of the CME changes the dynamic universality class to that of model A. We also show that the transport coefficient of the CME is not renormalized by the critical fluctuations of the order parameter.