Measurement of the anomalous like-sign dimuon charge asymmetry with 9 fb^-1 of pp̅ collisions

Abstract

We present an updated measurement of the anomalous like-sign dimuon charge asymmetry A_sl^b for semileptonic b-hadron decays in 9.0 fb^-1 of pp̅ collisions recorded with the D0 detector at a center-of-mass energy of √s=1.96 TeV at the Fermilab Tevatron collider. We obtain A_sl^b=(-0.787±0.172(stat)±0.093(syst))%. This result differs by 3.9 standard deviations from the prediction of the standard model and provides evidence for anomalously large CP violation in semileptonic neutral B decay. The dependence of the asymmetry on the muon impact parameter is consistent with the hypothesis that it originates from semileptonic b-hadron decays.