HIJING can describe the anisotropy-scaled charge-dependent correlations at the Relativistic Heavy Ion Collider

TL;DR

This paper demonstrates that the HIJING model, when properly scaled for elliptic anisotropy, can accurately reproduce charge-dependent correlations in heavy ion collisions, challenging the necessity of invoking the chiral magnetic effect.

Contribution

The study shows that the HIJING model can explain charge-dependent correlations without CME by accounting for elliptic anisotropy, contradicting previous assumptions.

Findings

HIJING's initial underestimation of correlations is due to low elliptic anisotropy.

Proper scaling of HIJING reproduces experimental charge-dependent correlations.

AMPT model also supports that CME is not required to explain the data.

Abstract

The experimentally measured charge-depdendent correlations in heavy ion collisions have been suggested as a signature of the chiral magenetic effect (CME). Early model studies could not reproduce the measurement. For example, the Hijing model yielded far smaller magnitude for the charge-dependent correlation than observed in data. This led to the conclusion that the CME had to be invoked to explain the observed correlations in heavy ion collisions. In this paper we show that this conclusion of the CME interpretation is premature. We show that the reason that Hijing predicts a far smaller correlation than data is because the elliptic anisotrpy ($v_{2}$) parameter in Hijing is too small. When properly scaled, the Hijing model can reproduce in entirety the measured correlations. We also employ the AMPT model, which has a large enough $v_2$, to demonstrate that the measured data can be easily accommodated by models without invoking the CME.