Moments of the<i>B</i>meson inclusive semileptonic decay rate using neutrino reconstruction

Abstract

We present a measurement of the composition of B meson inclusive semileptonic decays using 9.4 ${\mathrm{fb}}^{\mathrm{\ensuremath{-}}1}$ of ${e}^{+}{e}^{\ensuremath{-}}$ data taken with the CLEO detector at the $\ensuremath{\Upsilon}(4S)$ 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 $\stackrel{\ensuremath{\rightarrow}}{B}{X}_{c}\mathcal{l}\ensuremath{\nu}$ processes with ${X}_{c}=D,$ ${D}^{*},$ ${D}^{**},$ and nonresonant ${X}_{c},$ and the process $\stackrel{\ensuremath{\rightarrow}}{B}{X}_{u}\mathcal{l}\ensuremath{\nu}.$ From the fit results we extract the first and second moments of the ${M}_{X}^{2}$ and ${q}^{2}$ distributions with minimum lepton-energy requirements of 1.0 GeV and 1.5 GeV. We find $〈{M}_{X}^{2}\ensuremath{-}{M}_{D}^{2}〉=(0.456\ifmmode\pm\else\textpm\fi{}0.014\ifmmode\pm\else\textpm\fi{}0.045\ifmmode\pm\else\textpm\fi{}0.109){\mathrm{GeV}}^{2}{/c}^{4}$ with a minimum lepton energy of 1.0 GeV and $〈{M}_{X}^{2}\ensuremath{-}{M}_{D}^{2}〉=(0.293\ifmmode\pm\else\textpm\fi{}0.012\ifmmode\pm\else\textpm\fi{}0.033\ifmmode\pm\else\textpm\fi{}0.048){\mathrm{GeV}}^{2}{/c}^{4}$ 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 ${M}_{X}^{2}$ moment as a function of the minimum lepton energy requirement are compared to the predictions.