Moments of the B Meson Inclusive Semileptonic Decay Rate using Neutrino Reconstruction

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We present a measurement of the composition of B meson inclusive semileptonic decays using 9.4 fb-1 of e+e- data taken with the CLEO detector at the Upsilon(4S) resonance. In addition to measuring the charged lepton kinematics, the neutrino four-vector is inferred using the hermiticity of the detector. We perform a maximum likelihood fit over the full three-dimensional differential decay distribution for the fractional contributions from the B -> Xc l nu processes with Xc = D, D*, D**, and nonresonant Xc, and the process B -> Xᵤ l nu. From the fit results we extract the first and second moments of the Mₓ² and q² distributions with minimum lepton-energy requirements of 1.0 GeV and 1.5 GeV. We find <Mₓ² - MD[Bar]²> = 0.456 +- 0.014 +- 0.045 +- 0.109 (GeV/c²)² with a minimum lepton energy of 1.0 GeV and <Mₓ² - MD[Bar]²> = 0.293 +- 0.012 +- 0.033 +- 0.048 (GeV/c²)² with minimum lepton energy of 1.5 GeV. The uncertainties are from statistics, detector systematic effects, and model dependence, respectively. As a test of the HQET and OPE calculations, the results for the Mˣc moment as a function of the minimum lepton energy requirement are compared to the predictions.