Sliding dumbbell method to search for the CME in heavy-ion collisions

Abstract

This study explores the chiral magnetic effect (CME) in ultra-relativistic heavy-ion collisions. The CME, observed as back-to-back charge separation along the magnetic field axis, is investigated using the newly developed sliding dumbbell method (SDM) applied to Au\(+\)Au events at a centre-of-mass energy \(\sqrt{s}_{\text {NN}}=\) 200 GeV generated by the AMPT model with string melting configuration. The CME-like signal is externally injected in the events by flipping charges of pairs of particles perpendicular to the reaction plane. The study reports a significant enhancement of the CME-sensitive 3-particle \(\gamma \) correlator in events with high back-to-back charge separation, in a given collision centrality. Additionally, a linear relationship is observed between the \(\sqrt{|\gamma |}\) correlator for the same-sign charge pairs and positive charge asymmetry (\(\langle A^{+}\rangle \)) across the dumbbell in CME-enriched sub-samples. Furthermore, the fraction of CME in \(\Delta \gamma \) (difference between the opposite and same sign \(\gamma \) correlators) is presented across different collision centralities having different percentages of externally injected CME-like signal. Overall, the research aims to understand and detect the CME through innovative experimental method and detailed analysis of the event structure.