We determine the inclusive $B\to X_c\ell \nu$ branching fraction, ${\mathcal{B}}_{c\ell \nu }$, the Cabibbo-Kobayashi-Maskawa matrix element $\left|V_{cb}\right|$, and other heavy-quark parameters from a simultaneous fit to moments of the hadronic-mass and lepton-energy distributions in semileptonic $B$-meson decays, measured as a function of the lower limit on the lepton energy, using data recorded with the BABAR detector. Using heavy-quark expansions (HQEs) to order $1/m_b^3$, we extract ${\mathcal{B}}_{ce\nu }=(10.61\pm {0.16}_{\mathrm{e}\mathrm{x}\mathrm{p}}\pm {0.06}_{\mathrm{H}\mathrm{Q}\mathrm{E}})\%$ and $\left|V_{cb}\right|=(41.4\pm {0.4}_{\mathrm{e}\mathrm{x}\mathrm{p}}\pm {0.4}_{\mathrm{H}\mathrm{Q}\mathrm{E}}\pm {0.6}_{\mathrm{t}\mathrm{h}})\times {10}^{-3}$. The stated errors refer to the experimental, HQE, and additional theoretical uncertainties.

• Received 12 April 2004

DOI:https://doi.org/10.1103/PhysRevLett.93.011803