International audience; We report a measurement of the branching fraction of the semileptonic decay $B$$^{-}$ $\rightarrow$ $D$$^{0}$$\ell$$^{-}$$\bar{\nu}$$_{\ell}$ (and its charge conjugate) using 62.8 fb$^{-1}$ of $\Upsilon$(4$S$) $\rightarrow$ $B$$\bar{B}$ data recorded by the Belle II experiment at the SuperKEKB asymmetric-energy $e$$^{+}$ $e$$^{-}$ collider. The neutral charm meson is searched for in the decay mode $D$$^{0}$ $\rightarrow$ $K$$^{-}$ $\pi$$^{+}$ and combined with a properly charged identified lepton (electron or muon) to reconstruct this decay. No reconstruction of the second $B$ meson in the $\Upsilon$(4$S$) event is performed. We obtain $B$($D$$^{0}$$\ell$$^{-}$$\bar{\nu}$$_{\ell}$) = (2.29 $\pm$ 0.05 $_{stat}$ $\pm$ 0.08$_{syst}$, in agreement with the world average of this decay. We also determine the ratio of the electron to muon branching fractions to be $R$($e$/$\mu$) = 1.04 $\pm$ 0.05$_{stat}$ $\pm$ 0.03$_{syst}$ and observe no deviation from lepton universality.
Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut Pluridisciplinaire Hubert Curien (IPHC), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Centre de Physique des Particules de Marseille (CPPM), Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Belle-II
International audience; We report a measurement of the branching fraction of the semileptonic decay $B$$^{-}$ $\rightarrow$ $D$$^{0}$$\ell$$^{-}$$\bar{\nu}$$_{\ell}$ (and its charge conjugate) using 62.8 fb$^{-1}$ of $\Upsilon$(4$S$) $\rightarrow$ $B$$\bar{B}$ data recorded by the Belle II experiment at the SuperKEKB asymmetric-energy $e$$^{+}$ $e$$^{-}$ collider. The neutral charm meson is searched for in the decay mode $D$$^{0}$ $\rightarrow$ $K$$^{-}$ $\pi$$^{+}$ and combined with a properly charged identified lepton (electron or muon) to reconstruct this decay. No reconstruction of the second $B$ meson in the $\Upsilon$(4$S$) event is performed. We obtain $B$($D$$^{0}$$\ell$$^{-}$$\bar{\nu}$$_{\ell}$) = (2.29 $\pm$ 0.05 $_{stat}$ $\pm$ 0.08$_{syst}$, in agreement with the world average of this decay. We also determine the ratio of the electron to muon branching fractions to be $R$($e$/$\mu$) = 1.04 $\pm$ 0.05$_{stat}$ $\pm$ 0.03$_{syst}$ and observe no deviation from lepton universality.
