Sliding Dumbbell Method to search for the CME in heavy ion collisions

The deconfined state of matter created in the hot and dense medium in ultra-relativistic heavy-ion collisions causes the back-to-back charge separation along the direction of magnetic field produced due to the energetic spectator protons, a phenomenon known as the Chiral Magnetic Effect (CME). A new technique, the Sliding Dumbbell Method (SDM), is developed to search for the back-to-back charge separation on an event-by-event basis. The SDM is applied to AMPT generated Au+Au collision events with string melting configuration at $\sqrt{s}_{\mathrm{NN}}$ = 200 GeV. The varying percentages i.e., from $\sim$0.5\% to $\sim$8\%, of the CME like signals are externally injected in events by flipping charges of pairs of the particles perpendicular to the reaction plane. A significant enhancement of the CME sensitive 3-particle $\gamma$ correlator is reported for the events sub sample exhibiting the highest back-to-back charge separation for a given collision centrality. For the first time, we report the linear dependence of $\sqrt {|\gamma|}$ correlator for the same sign charge pairs on the positive charge asymmetry ($\langle A{^+}\rangle$) across the dumbbell for the CME enriched sub samples. The CME fraction in the observed $\Delta\gamma$ (difference between opposite and same sign $\gamma$ correlator) is also presented for different collision centralities with different percentages of externally injected CME like signal.