We report a measurement of the branching fractions for $\overline{B}\to D^{(*)}(\pi ){\ell }^{-}{\overline{\nu }}_{\ell }$ decays based on $341.1{\mathrm{fb}}^{-1}$ of data collected at the ${\rm Y}(4S)$ resonance with the BABAR detector at the SLAC PEP-II $e^{+}{e}^{-}$ storage rings. Events are tagged by fully reconstructing one of the $B$ mesons in a hadronic decay mode. We obtain $\mathcal{B}(B^{-}\to D^0{\ell }^{-}{\overline{\nu }}_{\ell })=(2.33\pm {0.09}_{\mathrm{stat}}\pm {0.09}_{\mathrm{syst}})\%$, $\mathcal{B}(B^{-}\to D^{*0}{\ell }^{-}{\overline{\nu }}_{\ell })=(5.83\pm {0.15}_{\mathrm{stat}}\pm {0.30}_{\mathrm{syst}})\%$, $\mathcal{B}({\overline{B}}^0\to D^{+}{\ell }^{-}{\overline{\nu }}_{\ell })=(2.21\pm {0.11}_{\mathrm{stat}}\pm {0.12}_{\mathrm{syst}})\%$, $\mathcal{B}({\overline{B}}^0\to D^{*+}{\ell }^{-}{\overline{\nu }}_{\ell })=(5.49\pm {0.16}_{\mathrm{stat}}\pm {0.25}_{\mathrm{syst}})\%$, $\mathcal{B}(B^{-}\to D^{+}{\pi }^{-}{\ell }^{-}{\overline{\nu }}_{\ell })=(0.42\pm {0.06}_{\mathrm{stat}}\pm {0.03}_{\mathrm{syst}})\%$, $\mathcal{B}(B^{-}\to D^{*+}{\pi }^{-}{\ell }^{-}{\overline{\nu }}_{\ell })=(0.59\pm {0.05}_{\mathrm{stat}}\pm {0.04}_{\mathrm{syst}})\%$, $\mathcal{B}({\overline{B}}^0\to D^0{\pi }^{+}{\ell }^{-}{\overline{\nu }}_{\ell })=(0.43\pm {0.08}_{\mathrm{stat}}\pm {0.03}_{\mathrm{syst}})\%$, and $\mathcal{B}({\overline{B}}^0\to D^{*0}{\pi }^{+}{\ell }^{-}{\overline{\nu }}_{\ell })=(0.48\pm {0.08}_{\mathrm{stat}}\pm {0.04}_{\mathrm{syst}})\%$.

• Received 20 December 2007

DOI:https://doi.org/10.1103/PhysRevLett.100.151802