Measurements of the branching fractions of the decays B0s→D∓sK± and B0s→D−sπ+

Abstract

The decay mode B0s→D∓sK± 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 B0s→D−sπ+ 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(B0s→D−sπ+)=(2.95±0.05±0.17+0.18−0.22)×10−3,B(B0s→D∓sK±)=(1.90±0.12±0.13+0.12−0.14)×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 .