Measurement of the relative branching fractions of B¯→D/D*/D**l−ν¯l decays in events with a fully reconstructed B meson

Le résumé fourni par la source

We determine the relative branching fractions of semileptonic $B$ decays to charmed final states. The measurement is performed on the recoil from a fully reconstructed $B$ meson in a sample of $362\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $B\overline{B}$ pairs collected at the $\ensuremath{\Upsilon}(4S)$ resonance with the BABAR detector. A simultaneous fit to a set of discriminating variables is performed on a sample of $\overline{B}\ensuremath{\rightarrow}DX{\ensuremath{\ell}}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{\ensuremath{\ell}}$ decays to determine the contributions from the different channels. We measure $\ensuremath{\Gamma}({B}^{\ensuremath{-}}\ensuremath{\rightarrow}D{\ensuremath{\ell}}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{\ensuremath{\ell}})/\ensuremath{\Gamma}({B}^{\ensuremath{-}}\ensuremath{\rightarrow}DX{\ensuremath{\ell}}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{\ensuremath{\ell}})=0.227\ifmmode\pm\else\textpm\fi{}0.014\ifmmode\pm\else\textpm\fi{}0.016$, $\ensuremath{\Gamma}({B}^{\ensuremath{-}}\ensuremath{\rightarrow}{D}^{*}{\ensuremath{\ell}}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{\ensuremath{\ell}})/\ensuremath{\Gamma}({B}^{\ensuremath{-}}\ensuremath{\rightarrow}DX{\ensuremath{\ell}}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{\ensuremath{\ell}})=0.582\ifmmode\pm\else\textpm\fi{}0.018\ifmmode\pm\else\textpm\fi{}0.030$, and $\ensuremath{\Gamma}({B}^{\ensuremath{-}}\ensuremath{\rightarrow}{D}^{**}{\ensuremath{\ell}}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{\ensuremath{\ell}})/\ensuremath{\Gamma}({B}^{\ensuremath{-}}\ensuremath{\rightarrow}DX{\ensuremath{\ell}}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{\ensuremath{\ell}})=0.191\ifmmode\pm\else\textpm\fi{}0.013\ifmmode\pm\else\textpm\fi{}0.019$ for the charged $B$ sample, and $\ensuremath{\Gamma}(\overline{{B}^{0}}\ensuremath{\rightarrow}D{\ensuremath{\ell}}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{\ensuremath{\ell}})/\ensuremath{\Gamma}(\overline{{B}^{0}}\ensuremath{\rightarrow}DX{\ensuremath{\ell}}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{\ensuremath{\ell}})=0.215\ifmmode\pm\else\textpm\fi{}0.016\ifmmode\pm\else\textpm\fi{}0.013$, $\ensuremath{\Gamma}(\overline{{B}^{0}}\ensuremath{\rightarrow}{D}^{*}{\ensuremath{\ell}}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{\ensuremath{\ell}})/\ensuremath{\Gamma}(\overline{{B}^{0}}\ensuremath{\rightarrow}DX{\ensuremath{\ell}}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{\ensuremath{\ell}})=0.537\ifmmode\pm\else\textpm\fi{}0.031\ifmmode\pm\else\textpm\fi{}0.036$, and $\ensuremath{\Gamma}(\overline{{B}^{0}}\ensuremath{\rightarrow}{D}^{**}{\ensuremath{\ell}}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{\ensuremath{\ell}})/\ensuremath{\Gamma}(\overline{{B}^{0}}\ensuremath{\rightarrow}DX{\ensuremath{\ell}}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{\ensuremath{\ell}})=0.248\ifmmode\pm\else\textpm\fi{}0.032\ifmmode\pm\else\textpm\fi{}0.030$ for the neutral $B$ sample, where uncertainties are statistical and systematic, respectively.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.