Charge dependent azimuthal correlations in Pb--Pb collisions at $\sqrt{s_{NN}} = 2.76$ TeV

TL;DR

This paper investigates charge-dependent azimuthal correlations in Pb--Pb collisions at 2.76 TeV to explore potential signals of local parity violation in strong interactions, comparing results with lower energy data and models.

Contribution

It provides the first detailed measurement of charge-dependent azimuthal correlations at LHC energies and assesses background effects using Monte Carlo simulations.

Findings

Charge-dependent correlations observed consistent with parity violation signals.

Comparison with RHIC data shows energy dependence of correlations.

Background effects are quantified and found to be manageable.

Abstract

Separation of charges along the extreme magnetic field created in non-central relativistic heavy--ion collisions is predicted to be a signature of local parity violation in strong interactions. We report on results for charge dependent two particle azimuthal correlations with respect to the reaction plane for Pb--Pb collisions at $\sqrt{s_{NN}} = 2.76$ TeV recorded in 2010 with ALICE at the LHC. The results are compared with measurements at RHIC energies and against currently available model predictions for LHC. Systematic studies of possible background effects including comparison with conventional (parity-even) correlations simulated with Monte Carlo event generators of heavy--ion collisions are also presented.