Measurements of the branching fractions of the decays Bs⁰→ Ds^∓ K± and B s⁰→ Ds^- π⁺

The decay mode Bs0 → Ds∓ K± allows for one of the theoretically cleanest measurements of the CKM angle γ through the study of time-dependent CP violation. This paper reports a measurement of its branching fraction relative to the Cabibbo-favoured mode Bs0 → Ds- π+ based on a data sample corresponding to 0.37 fb-1 of proton-proton collisions at √s = 7TeV collected in 2011 with the LHCb detector. In addition, the ratio of B meson production fractions fs=fd, determined from semileptonic decays, together with the known branching fraction of the control channel B0 → D-π+, is used to perform an absolute measurement of the branching fractions: B( Bs0 → D s- π+) = (2.95 ± 0.05 ± 0.17-0.22+0.18) × 10-3 ; B( B s0 → Ds∓ K ±) = (1.90 ± 0.12 ± 0.13-0.14+0.12) × 10-4 ; where the first uncertainty is statistical, the second the experimental systematic uncertainty, and the third the uncertainty due to fs=fd. Copyright CERN.