Constraining the chiral magnetic effect using spectator and participant planes across Au+Au and isobar collisions at $\sqrt{s_{_{\rm NN}}} = 200$ GeV

TL;DR

This study uses an improved two-plane method to analyze the chiral magnetic effect in heavy-ion collisions, revealing stronger CME signals in Au+Au collisions compared to isobar collisions, and demonstrating the method's reliability.

Contribution

It introduces an enhanced two-plane analysis technique for CME detection and compares its effectiveness across different collision systems.

Findings

Stronger CME signals observed in Au+Au collisions.

Reduced CME signal difference between spectator and participant planes in Au+Au.

Enhanced reliability of the two-plane method for CME detection.

Abstract

We investigate the chiral magnetic effect (CME) in relativistic heavy-ion collisions through an improved two-plane method analysis of the $\Delta\gamma$ observable, probing $\mathcal{CP}$-symmetry breaking in strong interactions and topological properties of the QCD vacuum. Using a multiphase transport model with tunable CME strengths, we systematically compare Au+Au and isobar collisions at $\sqrt{s_{_{\rm NN}}} = 200$ GeV. We observe a reduced difference in the CME signal-to-background ratio between the spectator and participant planes for Au+Au collisions compared to isobar collisions. A comprehensive chi-square analysis across all three collision systems reveals stronger CME signatures in Au+Au collisions relative to isobar collisions, particularly when measured with respect to the spectator plane. Our findings demonstrate an enhanced experimental reliability of the two-plane method for the CME detection in Au+Au collisions.