Measurement of charge multiplicity asymmetry correlations in high-energy nucleus-nucleus collisions at sNN=200 GeV

Le résumé fourni par la source

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 $\sqrt{{s}_{{}_{NN}}}=200$ 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, $\ensuremath{\Delta}$, 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 ${v}_{2}^{\mathrm{obs}}$), where $\ensuremath{\Delta}=[1.3\ifmmode\pm\else\textpm\fi{}1.4{(\mathrm{stat})}_{\ensuremath{-}1.0}^{+4.0}(\mathrm{syst})]\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}+[3.2\ifmmode\pm\else\textpm\fi{}0.2{(\mathrm{stat})}_{\ensuremath{-}0.3}^{+0.4}(\mathrm{syst})]\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}{v}_{2}^{\mathrm{obs}}$ for 20--40% Au + Au collisions. The implications for the proposed chiral magnetic effect are discussed.

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