Observation of $B_s^{0} \to D_s^{*-} π^{+}$, $B_s^{0} \to D_s^{(*)-} ρ^{+} $ and $B_s^{0} \to D_s^{(*)+} D_s^{(*)-}$ and Estimate of $ΔΓ_{CP}$ at Belle

Abstract

The large data sample being recorded with the Belle detector at the $Υ$(5S) energy provides a unique opportunity to study the less-well-known $B_s^{0}$ meson decays. Following our recent measurement of $B_s^{0}\to D_s^{-}π^{+}$ in a sample of 23.6 fb$^{-1}$, we extend the analysis to include decays with photons in the final state. Using the same sample, we report the first observation of three other dominant exclusive $B_s^{0}$ decays, in the modes $B_s^{0}\to D_s^{*-}π^+$, $B_s^{0}\to D_s^{-}ρ^+$ and $B_s^{0}\to D_s^{*-}ρ^+$. We measure their respective branching fractions and, using helicity-angle distributions, the longitudinal polarization fraction of the $B_s^{0}\to D_s^{*-}ρ^+$ decay. We also present a measurement of the branching fractions for the decays $B_s^{0} \to D_s^{(*)+}D_s^{(*)-}$. In the heavy quark limit, this branching fraction is directly related to the width difference between the $B_s$ CP-even and CP-odd eigenstates.