Real-time dynamics of axial charge and chiral magnetic current in a non-Abelian expanding plasma

TL;DR

This paper investigates the real-time evolution of axial charge and chiral magnetic current in an expanding non-Abelian plasma using holographic methods, revealing time-dependent relaxation rates and their effects on the CME.

Contribution

It introduces a holographic model to study axial charge relaxation and chiral magnetic current dynamics in an expanding plasma, accounting for time-dependent magnetic fields.

Findings

Axial charge relaxation rate varies with time due to magnetic field decay.

Established a horizon formula for the chiral magnetic current.

Analyzed the interplay of non-Abelian and Abelian anomalies in real-time.

Abstract

Understanding axial charge dynamics driven by changes in Chern-Simons number densities is a key aspect in understanding the chiral magnetic effect (CME) in heavy-ion collisions. Most phenomenological simulations assume that a large amount of axial charge is produced in the initial stages and that axial charge is conserved throughout the simulation. Within an (expanding) homogeneous holographic plasma, we investigate the real-time axial charge relaxation dynamics and their impact on the chiral magnetic current. Moreover, we discuss the real-time interplay of the non-Abelian and the Abelian chiral anomaly in the presence of a strong magnetic field. In the expanding plasma, the Chern-Simons diffusion rate and thus the axial charge relaxation rate are time dependent due to the decaying magnetic field. We quantify the changes in the late time falloffs and establish a horizon formula for the chiral magnetic current.