Measurement of the inclusive semileptonic branching fraction of B mesons and |Vcb|

Abstract We present a measurement of the electron spectrum from inclusive semileptonic B decay, using 5.1 fb −1 of ϒ (4 S ) data collected with the Belle detector. A high-momentum lepton tag was used to separate the semileptonic B decay electrons from secondary decay electrons. We obtained the branching fraction, B (B→Xe + ν)=(10.90±0.12±0.49)% , with minimal model dependence. From this measurement, we derive a value for the Cabibbo–Kobayashi–Maskawa matrix element | V cb |=0.0408±0.0010(exp)±0.0025(th).