Charge asymmetry dependence of flow and a novel correlator to detect the chiral magnetic wave in a multiphase transport model

TL;DR

This study investigates charge asymmetry effects on flow in heavy-ion collisions and introduces a new correlator to detect the chiral magnetic wave, offering a potentially clearer signal than previous methods.

Contribution

A novel correlator $W$ is proposed that isolates the chiral magnetic wave signal from charge asymmetry effects in heavy-ion collisions.

Findings

The correlator $W_2$ shows convex shape without quadrupole and concave with quadrupole.

The method effectively distinguishes the chiral magnetic wave signal from background.

Analytical and toy model studies support the correlator's sensitivity.

Abstract

In a multiphase transport model with the initial electric quadrupole moment, we studied and discussed the charge asymmetry ($A_{\rm ch}$) dependence of flow at varied kinematic windows in semi-central Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 200 GeV. We then proposed a novel correlator $W$ which specially focuses on the difference of elliptic flow between positively and negatively charged hadrons induced by the chiral magnetic wave and, more importantly, is irrelevant to the ambiguous $A_{\rm ch}$. We found that the distribution of the second order correlator $W_2$ displays a convex structure in the absence of the quadrupole and a concave shape in the presence of the quadrupole. We also studied the response of $W_n$ for both signal and resonance background in a toy model and in analytical calculation. Such a method provides a new way to detect the chiral magnetic wave.