Measurement of |V_cb| and the Form-Factor Slope in Bbar -> D l- nubar Decays in Events Tagged by a Fully Reconstructed B Meson

Abstract

We present a measurement of the Cabibbo-Kobayashi-Maskawa matrix element |V_cb| and the form-factor slope rho^2 in Bbar -> Dl- nubar decays based on 460 million BBar events recorded at the Upsilon(4S) resonance with the BaBar detector. BBar -> Dl- nubar decays are selected in events in which a hadronic decay of the second B meson is fully reconstructed. We measure the differential decay rate and determine G(1) |V_cb|= (43.0 \pm 1.9 \pm 1.4)\times 10^{-3} and rho^2 = 1.20 \pm 0.09 \pm 0.04, where G(1) is the the hadronic form factor at the point of zero recoil. We also determine the exclusive branching fractions and find BF(B^- -> D0l- nubar) = (2.31 \pm 0.08 \pm 0.09)% and BF (B0bar -> D+ l^- nubar)=(2.23 \pm 0.11 \pm 0.11)%.