Charge-dependent anisotropic flow studies and the search for the Chiral Magnetic Wave in ALICE

TL;DR

This paper reports charge-dependent anisotropic flow measurements in Pb--Pb collisions at 2.76 TeV to investigate the presence of the Chiral Magnetic Wave, a phenomenon predicted by QCD related to magnetic fields and P-violation.

Contribution

It presents the first set of experimental charge-dependent flow measurements in heavy-ion collisions aimed at detecting the Chiral Magnetic Wave in ALICE.

Findings

No definitive evidence of the CMW was observed.

Charge-dependent flow correlators showed expected patterns but no conclusive CMW signal.

Results constrain the possible strength of the CMW in heavy-ion collisions.

Abstract

Theoretical calculations have shown the possibility of P-violating bubbles in the QCD vacuum, which in combination with the strong magnetic field created in off-central heavy-ion collisions lead to novel effects such as the Chiral Magnetic Effect (CME) and the Chiral Separation Effect (CSE). A coupling between the CME and the CSE produces a wave-like excitation called the Chiral Magnetic Wave (CMW). The CMW produces a quadrupole moment that always has the same sign and is therefore present in an average over events. In this talk we present a series of charge-dependent anisotropic flow measurements in Pb--Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV in ALICE, using two- and three-particle correlators with unidentified hadrons. The relation of these measurements to the search for the CMW is discussed.