Scaling properties of background- and chiral-magnetically-driven charge separation: Implications for the chiral magnetic effect in heavy ion collisions

Abstract

The scaling properties of the RΨ2(∆S) correlator and the Δγ correlator are used to investigate a possible chiral-magnetically-driven (CME) charge separation in p+Au, d+Au, Ru+Ru, Zr+Zr, and Au+Au collisions at √SNN = 200 GeV, and in p+Pb (√SNN = 5.02 TeV) and Pb+Pb collisions at √SNN = 5.02 and 2:76 TeV. The results for p+Au, d+Au, p+Pb, and Pb+Pb collisions, show the 1/Nch scaling for background-driven charge separation. However, the results for Au+Au, Ru+Ru, and Zr+Zr collisions show scaling violations which indicate a CME contribution in the presence of a large background. In mid-central collisions, the CME accounts for approximately 27% of the signal + background in Au+Au and roughly a factor of two smaller for Ru+Ru and Zr+Zr, which show similar magnitudes.