Measurement of the Semileptonic C P Asymmetry in B0 - ̄B0 Mixing

Abstract

The semileptonic CP asymmetry in B0-¯B0 mixing, adsl, is measured in proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb−1, recorded by the LHCb experiment. Semileptonic B0 decays are reconstructed in the inclusive final states D−μ+ and D*−μ+, where the D− meson decays into the K+π−π− final state and the D*− meson into the ¯D0(→K+π−)π− final state. The asymmetry between the numbers of D(*)−μ+ and D(*)+μ− decays is measured as a function of the decay time of the B0 mesons. The CP asymmetry is measured to be adsl=(−0.02±0.19±0.30)%, where the first uncertainty is statistical and the second systematic. This is the most precise measurement of adsl to date and is consistent with the prediction from the standard model.