Measurement of the Branching Fractions of B¯→D**ℓ-ν¯ℓ Decays in Events Tagged by a Fully Reconstructed B Meson

We report a measurement of the branching fractions of B̅ →D**ℓ-ν̅ ℓ decays based on 417  fb-1 of data collected at the Υ(4S) resonance with the BABAR detector at the PEP-II e+e- storage rings. Events are selected by fully reconstructing one of the B mesons in a hadronic decay mode. A fit to the invariant mass differences m(D(*)π)-m(D(*)) is performed to extract the signal yields of the different D** states. We observe the B̅ →D**ℓ-ν̅ ℓ decay modes corresponding to the four D** states predicted by heavy quark symmetry with a significance greater than 5 standard deviations including systematic uncertainties.