Measurement of the inclusive semileptonic branching fraction $\mathcal{B}({B}_{s}^{0}\ensuremath{\rightarrow}{X}^{\ensuremath{-}}{\ensuremath{\ell}}^{+}{\ensuremath{\nu}}_{\ensuremath{\ell}})$ at Belle

Measurement of the inclusive semileptonic branching fraction $B (B_{s}^{0} \to X^{-} ℓ^{+} ν_{ℓ})$ at Belle

C. Oswald et al. (Belle Collaboration)

Phys. Rev. D 87, 072008 – Published 30 April 2013; Erratum Phys. Rev. D 90, 119901 (2014)

Abstract

We report a measurement of the inclusive semileptonic $B_{s}^{0}$ branching fraction in a $121 {fb}^{- 1}$ data sample collected near the $Υ (5 S)$ resonance with the Belle detector at the KEKB asymmetric energy $e^{+} e^{-}$ collider. Events containing $B_{s}^{0 (*)} {\bar{B}}_{s}^{0 (*)}$ pairs are selected by reconstructing a tag side $D_{s}^{+}$ and identifying a signal side lepton $ℓ^{+}$ ( $ℓ = e$ , $μ$ ) that is required to have the same-sign charge to ensure that both originate from different $B_{s}^{0}$ mesons. The $B_{s}^{0} \to X^{-} ℓ^{+} ν_{ℓ}$ branching fraction is extracted from the ratio of the measured yields of $D_{s}^{+}$ mesons and $D_{s}^{+} ℓ^{+}$ pairs and the known production and branching fractions. The inclusive semileptonic branching fraction is measured to be $[10.6 \pm 0.5 (stat) \pm 0.7 (syst)] %$ .