Disentangling Flow Contributions from the Chiral Magnetic Effect in U+U Collisions with Forward-Backward Multiplicity Asymmetry

TL;DR

This paper proposes using forward-backward multiplicity asymmetry (FBMA) as a practical method to distinguish the Chiral Magnetic Effect signal from flow backgrounds in heavy-ion U+U collisions.

Contribution

It introduces FBMA as an experimentally accessible control parameter to separate CME signals from flow backgrounds, especially in deformed nuclei collisions.

Findings

FBMA correlates with initial-state geometry and modulates ellipticity independently of magnetic-field correlator.

Monte Carlo Glauber simulations support FBMA's effectiveness in disentangling CME signals from flow backgrounds.

FBMA variation within fixed centrality class helps isolate CME signals in heavy-ion collisions.

Abstract

The observation of the Chiral Magnetic Effect (CME) in heavy-ion collisions remains challenging because of large flow-induced backgrounds and experimental constraints. We demonstrate that the forward-backward multiplicity asymmetry (FBMA) provides a robust and experimentally accessible control parameter to separate the flow background from CME signal in the collisions of deformed nuclei, such as prolate uranium where FBMA is naturally enhanced and correlated with the initial-state geometry. Monte Carlo Glauber simulations indicate that varying FBMA within a fixed centrality class modulates ellipticity largely independently of the magnetic-field correlator, establishing FBMA as a practical tool for disentangling CME signals from flow driven background.