| This document presents a new measurement of inclusive b semileptonic branching fractions Bb→l and B&parl0;b→c→l&parr0; . The b→l and b→c→l are separated by a means that uses correlation between the final state lepton charge and that of its parent b quark as a constraint. Monte Carlo counts of electrons and muons are calibrated to the data using a newly developed technique based on pairs of mutually independent tests for each particle hypothesis separately. The data sample consists of about 550,000 hadronic Z decays collected at the SLD between 1993 and 1998. Upon analysis of electron and muon counts in 61602 hadronic event hemispheres tagged as containing either a b or a b¯, we report Bb→e=0.0 949+/-0.0049+/-0.0050 Bb→m =0.1066+/-0.0038+/-0.0049 combinedB b→l=0.1015+/-0.0 030+/-0.0035 Bb→c→e =0.0811+/-0.0053+/-0.0030 Bb→c→m =0.0717+/-0.0045+/-0.0024 combinedB b→c→l=0.0756+/- 0.0034+/-0.0019. . |
