MEASUREMENT OF THE INCLUSIVE ELECTRON SPECTRUM IN CHARMLESS SEMILEPTONIC B DECAYS NEAR THE KINEMATIC ENDPOINT

A preliminary result on the study of the inclusive electron spectrum in B → Xueν decays above the kinematic limit for the dominant B → Xueν transitions is presented. This study is performed at the PEP-II asymmetric B Factory, where B meson pairs are produced in the decay of the Υ(4S) resonance. For the electron momentum range of 2.3 - 2.6 GeV/c in the Υ(4S) rest frame, the partial branching ratio is measured to be ΔΒ(B → Xueν) = (0.152 ± 0.014 ± 0.014) · 10-3