Event-shape-engineering study of charge separation in heavy-ion collisions

TL;DR

This paper investigates charge separation in heavy-ion collisions, proposing an event-shape engineering method to distinguish the genuine chiral magnetic effect signal from flow-related background using simulations.

Contribution

It introduces a novel event-shape engineering scheme to isolate the true CME signal by utilizing the flow vector, improving background subtraction in charge-dependent correlations.

Findings

The method effectively reduces flow background contamination.

Simulations demonstrate improved CME signal extraction.

The approach provides a new tool for analyzing charge separation signals.

Abstract

Recent measurements of charge-dependent azimuthal correlations in high-energy heavy-ion collisions have indicated charge-separation signals perpendicular to the reaction plane, and have been related to the chiral magnetic effect (CME). However, the correlation signal is contaminated with the background caused by the collective motion (flow) of the collision system, and an effective approach is needed to remove the flow background from the correlation. We present a method study with simplified Monte Carlo simulations and a multi-phase transport model, and develop a scheme to reveal the true CME signal via the event-shape engineering with the flow vector of the particles of interest.