Measurement of the B^¯→Dlv^¯ partial width and form factor parameters

We have studied the decayB^¯→Dlν^¯ where l = e or μ. From a fit to the differential decay ratedγ/dwwe measure the rate normalizationF_D(1) |V cb | and form factor slopeρ^ˆ2_D, and, using measured values ofτ_B, findγ(B^¯→Dlv^¯) = (12.0 ± 0.9 ± 2.1) ns⁻¹ . The resulting branching fractions areB (B^¯0 → D⁺ l^−ν¯) = (1.87 ± 0.15 ± 0.32)% and B (B⁻ → D⁰l⁻ν^¯) = (1.94 ± 0.15 ± 0.34)% . The form factor parameters are in agreement with those measured in B^¯ → D*l⁻ν^¯ decays, as predicted by heavy quark effective theory.