Charge-Dependent Correlations in Relativistic Heavy Ion Collisions and the Chiral Magnetic Effect

TL;DR

This paper analyzes experimental searches for the Chiral Magnetic Effect in heavy ion collisions, highlighting ambiguous evidence and emphasizing the need to understand background effects for conclusive results.

Contribution

It introduces correlation functions for detecting the Chiral Magnetic Effect and critically assesses current experimental evidence and background contributions.

Findings

Current evidence for the Chiral Magnetic Effect is ambiguous.

Background effects from conventional physics complicate interpretation.

Further quantitative understanding of backgrounds is necessary.

Abstract

We provide a phenomenological analysis of present experimental searches for local parity violation manifested through the Chiral Magnetic Effect. We introduce and discuss the relevant correlation functions used for the measurements. Our analysis of the available data from both RHIC and LHC shows that the present experimental evidence for the Chiral Magnetic Effect is rather ambiguous. We further discuss in some detail various background contributions due to conventional physics, which need to be understood quantitatively in order to draw a definitive conclusion about the existence of local parity violation in heavy ion collisions.