We have studied the production of B mesons in e+e- annihilations and present new measurements of the semileptonic branching fractions for B-meson decay. We find B(B=eX)=0.127±0.017±0.013 and B(B=X)=0.122±0.017±0.031, where the errors are statistical and systematic, respectively. The observed lepton momentum spectra from B decays are presented. From these spectra we find the mean hadronic mass (MX) recoiling against the detected lepton to be MX=2.2±0.2 GeV/c2. We have also observed an enhancement in the lepton yield from the continuum above BB» threshold. This enhancement is interpreted as continuum B production and is consistent with what is expected from the naive quark model.
Bibliographical noteFunding Information:
• This research was supported by the UK Science and Engineering Research Council under grants GR/G 32779 and GR/J 21347. I thank my colleagues from the UKQCD Collaboration and G. Martlnelli for fruitful discussions.