Electric Fields and Chiral Magnetic Effect in Cu + Au Collisions

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 ${\gamma }_{q_1{q}_2}=<\cos ({\varphi }_1+{\varphi }_2-2{\psi }_{RP})>$ (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 ${\gamma }_{q_1{q}_2}$ 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 ${\gamma }_{q_1{q}_2}$.

Comments: V1: 7 pages, 8 figures. V2: Add 2 new figures. Published version