Investigation of the Chiral Magnetic Effect using Event Shape Engineering in Pb–Pb collisions at √sNN = 5.02 TeV

The fluctuations in the initial energy density of heavy-ion collisions, reflected in the event-by-event variation of elliptic flow v2, allow an efficient selection of events corresponding to specific initial geometries. This technique, Event Shape Engineering, has been used to search for the Chiral Magnetic Effect (CME), a parity violating effect of the strong interaction. The three-particle correlator γαβ = hcos(ϕα + ϕβ − 2Ψ2)i, calculated for different combinations of charges α and β, has been employed to disentangle the CME signal from background effects in Pb–Pb collisions at √sNN = 5.02 TeV recorded by the ALICE detector. In order to constrain the CME contribution to the measured correlations, the charge-dependence of γαβ is compared with the expectations for the CME signal based on Monte Carlo calculations with magnetic field of spectators.