Axial Charge Fluctuation and Chiral Magnetic Effect from Stochastic Hydrodynamics

TL;DR

This paper investigates axial charge fluctuations in heavy ion collisions using stochastic hydrodynamics, challenging previous assumptions and providing a new perspective on the chiral magnetic effect consistent with experimental data.

Contribution

It introduces a stochastic hydrodynamics framework to model axial charge fluctuations, suggesting a thermodynamic limit approach that better matches experimental observations.

Findings

Axial charge fluctuations may approach thermodynamic limit in heavy ion collisions.

The model reproduces the centrality dependence of charged particle correlations.

Chiral magnetic effect estimates are refined using thermodynamic limit assumptions.

Abstract

The amount of axial charge produced in heavy ion collisions is one of the key quantities in understanding chiral magnetic effect. Current phenomenological studies assume large axial charge chemical potential $\mu_5$ produced in Glasma phase and assume the conservation of axial charge throughout the evolution, which is valid in the long relaxation time limit. Based on the solution of stochastic hydrodynamics with phenomenological parameters, our study suggests that the situation of heavy ion collisions may be close to the opposite limit, in which axial charge fluctuation approaches thermodynamic limit. Using $\mu_5$ set by the thermodynamic limit for chiral magnetic effect and a background from parity-even $v_1$, we obtain a reasonable description of the centrality dependence of charged particle correlation measured in experiment.