Measurement of the inclusive electron spectrum in charmless semileptonic B decays near the kinematic end point and determination of |Vub|

Le résumé fourni par la source

We present a measurement of the inclusive electron spectrum in $B\ensuremath{\rightarrow}{X}_{u}e\ensuremath{\nu}$ decays near the kinematic limit for $B\ensuremath{\rightarrow}{X}_{c}e\ensuremath{\nu}$ transitions, using a sample of $88\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $B\overline{B}$ pairs recorded by the BABAR detector at the $\ensuremath{\Upsilon}(4S)$ resonance. Partial branching fraction measurements are performed in five overlapping intervals of the electron momentum; for the interval of $2.0--2.6\text{ }\mathrm{GeV}/c$ we obtain $\ensuremath{\Delta}\mathcal{B}(B\ensuremath{\rightarrow}{X}_{u}e\ensuremath{\nu})=(0.572\ifmmode\pm\else\textpm\fi{}{0.041}_{\mathrm{stat}}\ifmmode\pm\else\textpm\fi{}{0.065}_{\mathrm{syst}})\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$. Combining this result with shape function parameters extracted from BABAR measurements of moments of the inclusive photon spectrum in $B\ensuremath{\rightarrow}{X}_{s}\ensuremath{\gamma}$ decays and moments of the hadron-mass and lepton-energy spectra in $B\ensuremath{\rightarrow}{X}_{c}\ensuremath{\ell}\ensuremath{\nu}$ decays we determine $|{V}_{ub}|=(4.44\ifmmode\pm\else\textpm\fi{}{0.25}_{\mathrm{exp}\ensuremath{-}0.38SF}^{+0.42}\ifmmode\pm\else\textpm\fi{}{0.22}_{\mathrm{theory}})\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$. Here the first error represents the combined statistical and systematic experimental uncertainties of the partial branching fraction measurement, the second error refers to the uncertainty of the determination of the shape function parameters, and the third error is due to theoretical uncertainties in the QCD calculations.

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