Measurement of the inclusive electron spectrum in charmless semileptonic B decays near the kinematic end point and determination of |Vub| -: art. no. 012006

We present a measurement of the inclusive electron spectrum in B -> X(u)e nu decays near the kinematic limit for B -> X(c)e nu transitions, using a sample of 88 x 10(6) B (B) over bar pairs recorded by the BABAR detector at the 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 GeV/c we obtain Delta B(B -> X(u)e nu) = (0.572 +/- 0.041(stat) +/- 0.065(syst)) x 10(-3). Combining this result with shape function parameters extracted from BABAR measurements of moments of the inclusive photon spectrum in B -> X(s)gamma decays and moments of the hadron-mass and lepton-energy spectra in B -> X(c)l nu decays we determine vertical bar V(ub)vertical bar = (4.44 +/- 0.25(exp-0.38SF)(+0.42) +/- 0.22(theory)) x 10(-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.