# Isolating the chiral magnetic effect from backgrounds by pair invariant mass

## TL;DR

This paper proposes a novel method to isolate the chiral magnetic effect in heavy ion collisions by analyzing the pair invariant mass dependence of charge correlations, aiming to reduce background interference.

## Contribution

It introduces a differential measurement approach based on pair invariant mass to distinguish the CME signal from background effects in experimental data.

## Key findings

- Model studies show the method's feasibility.
- High invariant mass regions reduce background influence.
- The approach enhances CME detection sensitivity.

## Abstract

Topological gluon configurations in quantum chromodynamics induce quark chirality imbalance in local domains, which can result in the chiral magnetic effect (CME)--an electric charge separation along a strong magnetic field. Experimental searches for the CME in relativistic heavy ion collisions via the charge-dependent azimuthal correlator ($\Delta\gamma$) suffer from large backgrounds arising from particle correlations (e.g. due to resonance decays) coupled with the elliptic anisotropy. We propose differential measurements of the $\Delta\gamma$ as a function of the pair invariant mass ($m_{\rm inv}$), by restricting to high $m_{\rm inv}$ thus relatively background free, and by studying the $m_{\rm inv}$ dependence to separate the possible CME signal from backgrounds. We demonstrate by model studies the feasibility and effectiveness of such measurements for the CME search.