Measurement of the relative $B^{-}\to D^0/D^{\ast 0}/D^{\ast \ast 0}{\mu }^{-}{\overline{\nu }}_{\mu }$ branching fractions using $B^{-}$ mesons from $\overline{B}{}_{s2}^{\ast 0}$ decays

Abstract

The decay of the narrow resonance $\overline{B}{}_{s2}^{\ast 0}\to B^{-}{K}^{+}$ can be used to determine the $B^{-}$ momentum in partially reconstructed decays without any assumptions on the decay products of the $B^{-}$ meson. This technique is employed for the first time to distinguish contributions from $D^0$, $D^{\ast 0}$, and higher-mass charmed states ($D^{\ast \ast 0}$) in semileptonic $B^{-}$ decays by using the missing-mass distribution. The measurement is performed using a data sample corresponding to an integrated luminosity of 3.0 fb${}^{-1}$ collected with the LHCb detector in $pp$ collisions at center-of-mass energies of 7 and 8 TeV. The resulting branching fractions relative to the inclusive $B^{-}\to D^{0}X{\mu }^{-}{\overline{\nu }}_{\mu }$ are $f_{D^0}=\mathcal{B}(B^{-}\to D^0{\mu }^{-}{\overline{\nu }}_{\mu })/\mathcal{B}(B^{-}\to D^{0}X{\mu }^{-}{\overline{\nu }}_{\mu })=0.25\pm 0.06$, $f_{D^{\ast \ast 0}}=\mathcal{B}(B^{-}\to (D^{\ast \ast 0}\to D^{0}X){\mu }^{-}{\overline{\nu }}_{\mu })/\mathcal{B}(B^{-}\to D^{0}X{\mu }^{-}{\overline{\nu }}_{\mu })=0.21\pm 0.07$, with $f_{D^{\ast 0}}=1-f_{D^0}-f_{D^{\ast \ast 0}}$ making up the remainder.

All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2018-024.html . v2 includes minor text changes and two additional subfigures added during journal review