Measurement of the branching fraction of the B0→ D+s π− decay

A branching fraction measurement of the B0→D+s π− decay is presented using proton–proton collision data collected with the LHCb experiment, corresponding to an integrated luminosity of 5.0 fb−1 . The branching fraction is found to be B(B0→D+s π−) = (19.4±1.8 ± 1.3 ± 1.2) × 10−6 , where the first uncertainty is statistical, the second systematic and the third is due to
the uncertainty on the B0→D−π+, D+s →K + K −π+ and D− →K +π−π− branching fractions. This is the most precise single measurement of this quantity to date. As this decay proceeds through a single amplitude involving a b→u charged-current transition, the result provides information on non-factorisable strong interaction effects and the magnitude of the Cabibbo–Kobayashi–Maskawa matrix element Vub. Additionally, the collision energy dependence of the hadronisation-fraction ratio f s / f d is measured through B0s →D+s π− and B0→D−π+ decays.