Measurement of the branching fraction of the ${{B} ^0} {\rightarrow }{{D} ^+_{s}} {{\pi } ^-} $ decay
A branching fraction measurement of the \({{B} ^0} {\rightarrow }{{D} ^+_{s}} {{\pi } ^-} \) decay is presented using proton–proton collision data collected with the LHCb experiment, corresponding to an integrated luminosity of \(5.0\,\text {fb} ^{-1} \) . The branching fraction is found to be \({\mathcal {B}} ({{B} ^0} {\rightarrow }{{D} ^+_{s}} {{\pi } ^-} ) =(19.4 \pm \) \(1.8\pm 1.3 \pm 1.2)\times 10^{-6}\) , where the first uncertainty is statistical, the second systematic and the third is due to the uncertainty on the \({{B} ^0} {\rightarrow }{{D} ^-} {{\pi } ^+} \) , \({{D} ^+_{s}} {\rightarrow }{{K} ^+} {{K} ^-} {{\pi } ^+} \) and \({{D} ^-} {\rightarrow }{{K} ^+} {{\pi } ^-} {{\pi } ^-} \) branching fractions. This is the most precise single measurement of this quantity to date. As this decay proceeds through a single amplitude involving a \(b{\rightarrow }u\) charged-current transition, the result provides information on non-factorisable strong interaction effects and the magnitude of the Cabibbo–Kobayashi–Maskawa matrix element \(V_{ub}\) . Additionally, the collision energy dependence of the hadronisation-fraction ratio \(f_s/f_d\) is measured through \({{\overline{B}} {}^0_{s}} {\rightarrow }{{D} ^+_{s}} {{\pi } ^-} \) and \({{B} ^0} {\rightarrow }{{D} ^-} {{\pi } ^+} \) decays.