Measurements of the semileptonic decays B¯→Dℓν¯ and B¯→D*ℓν¯ using a global fit to DXℓν¯ final states

Semileptonic B̅ decays to DXℓν̅ (ℓ=e or μ) are selected by reconstructing D0ℓ and D+ℓ combinations from a sample of 230×106 Υ(4S)→BB̅ decays recorded with the BABAR detector at the PEP-II e+e- collider at SLAC. A global fit to these samples in a three-dimensional space of kinematic variables is used to determine the branching fractions B(B-→D0ℓν̅ )=(2.34±0.03±0.13)% and B(B-→D*0ℓν̅ )=(5.40±0.02±0.21)% where the errors are statistical and systematic, respectively. The fit also determines form-factor parameters in a parametrization based on heavy quark effective theory, resulting in ρD2=1.20±0.04±0.07 for B̅ →Dℓν̅ and ρD*2=1.22±0.02±0.07 for B̅ →D*ℓν̅ . These values are used to obtain the product of the Cabibbo-Kobayashi-Maskawa matrix element |Vcb| times the form factor at the zero recoil point for both B̅ →Dℓν̅ decays, G(1)|Vcb|=(43.1±0.8±2.3)×10-3, and for B̅ →D*ℓν̅ decays, F(1)|Vcb|=(35.9±0.2±1.2)×10-3.