Determination of the HQET parameterλ1from an inclusive semileptonicBmeson decay spectrum

Abstract

We estimate the heavy quark effective theory parameter ${\ensuremath{\lambda}}_{1}$ from the inclusive semileptonic B-meson decay spectrum. By using recent CLEO double lepton tagging data of $\stackrel{\ensuremath{\rightarrow}}{B}\mathrm{Xe}\ensuremath{\nu}$, which show the lepton momentum as low as 0.6 GeV, we extracted ${\ensuremath{\lambda}}_{1}\ensuremath{\sim}\ensuremath{-}0.58 {\mathrm{GeV}}^{2}$. We also derived $\overline{\ensuremath{\Lambda}}\ensuremath{\sim}0.46 \mathrm{GeV}$ and $|{V}_{\mathrm{cb}}|=0.041\ifmmode\pm\else\textpm\fi{}0.002$.