Measurement of the flavour-specific CP-violating asymmetry a[s over sl] in B[0 over s] decays

Abstract

The CP -violating asymmetry a[s over ls] is studied using semileptonic decays of B[0 over s] and [¯ over B][0 over s] mesons produced in pp collisions at a centre-of-mass energy of 7 TeV at the LHC, exploiting a data sample corresponding to an integrated luminosity of 1.0 fb[superscript −1]. The reconstructed final states are D[± over s]μ[superscript ∓], with the D[± over s] particle decaying in the ϕπ[superscript ±] mode. The D[± over s]μ[superscript ∓] yields are summed over [¯ over B][0 over s] and B[0 over s] initial states, and integrated with respect to decay time. Data-driven methods are used to measure efficiency ratios. We obtain a[s over ls] = (−0.06±0.50±0.36)%, where the first uncertainty is statistical and the second systematic.