Title

Measurement of Charge Multiplicity Asymmetry Correlations in High-Energy Nucleus-Nucleus Collisions at Root S-NN=200 GeV

Document Type

Article

Publication Date

4-2014

Abstract

A study is reported of the same-and opposite-sign charge-dependent azimuthal correlations with respect to the event plane in Au+ Au collisions at root(S)(NN) = 200 GeV. The charge multiplicity asymmetries between the up/down and left/right hemispheres relative to the event plane are utilized. The contributions from statistical fluctuations and detector effects were subtracted from the (co-) variance of the observed charge multiplicity asymmetries. In the mid-to most-central collisions, the same- (opposite-) sign pairs are preferentially emitted in back-to-back (aligned on the same-side) directions. The charge separation across the event plane, measured by the difference, Delta, between the like-and unlike-sign up/down-left/right correlations, is largest near the event plane. The difference is found to be proportional to the event-by-event final-state particle ellipticity (via the observed second order harmonic nu(obs)(2)), where Delta = [ 1.3 +/- 1.4( stat)(-1.0)(+4.0)(syst)] x 10(-5) + [3.2 +/- 0.2(stat)(- 0.3)(+0.4)(syst)] x 10(-3)v(2)(obs) for 20- 40% Au + Au collisions. The implications for the proposed chiral magnetic effect are discussed.