Measurement of the ratio B(B+ → Xeν) / B(B0 → Xeν)

Abstract

We report measurements of the inclusive electron momentum spectra in decays of charged and neutral B mesons, and of the ratio of semileptonic branching fractions B ( B + → X e ν ) and B ( B 0 → X e ν ) . These were performed on a sample of 231 × 10 6 B ¯¯¯ B events recorded with the BABAR detector at the Υ ( 4 S ) resonance. Events are selected by fully reconstructing a hadronic decay of one B meson and identifying an electron among the decay products of the recoiling ¯¯¯ B meson. We obtain B ( B + → X e ν ) / B ( B 0 → X e ν ) = 1.074 ± 0.041 ( stat ) ± 0.026 ( syst ) .