Measurements of the branching fractions of the decays B s0→ D s∓ K± and B s0→ D s- π +

The decay mode B s0 → D s∓ 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 B s0 → D s- 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 f s=f d, determined from semileptonic decays, together with the known branching fraction of the control channel B 0 → D -π +, is used to perform an absolute measurement of the branching fractions: B( B s0 → D s- π +) = (2.95 ± 0.05 ± 0.17 -0.22+0.18) × 10 -3 ; B( B s0 → D s∓ 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 f s=f d. Copyright CERN.