Electric Fields and Chiral Magnetic Effect in Cu + Au Collisions

TL;DR

This study investigates electromagnetic fields in Cu + Au collisions at 200 GeV and their effects on charge-dependent correlations, providing insights into the detection of the chiral magnetic effect and the influence of electric fields.

Contribution

The paper introduces a detailed analysis of electromagnetic fields in Cu + Au collisions and their impact on charge correlations, offering a new approach to test the chiral magnetic effect.

Findings

In-plane electric fields can suppress or reverse the charge-dependent correlator.

Cu + Au collisions provide a unique environment to distinguish CME signals from background effects.

Electric field lifetime significantly influences the charge correlation measurements.

Abstract

The non-central Cu + Au collisions can create strong out-of-plane magnetic fields and in-plane electric fields. By using the HIJING model, we study the general properties of the electromagnetic fields in Cu + Au collisions at 200 GeV and their impacts on the charge-dependent two-particle correlator $\gamma_{q_1q_2}=<\cos(\phi_1+\phi_2-2\psi_{RP})>$ (see main text for definition) which was used for the detection of the chiral magnetic effect (CME). Compared with Au + Au collisions, we find that the in-plane electric fields in Cu + Au collisions can strongly suppress the two-particle correlator or even reverse its sign if the lifetime of the electric fields is long. Combining with the expectation that if $\gamma_{q_1q_2}$ is induced by elliptic-flow driven effects we would not see such strong suppression or reversion, our results suggest to use Cu + Au collisions to test CME and understand the mechanisms that underlie $\gamma_{q_1q_2}$.