Semileptonic B-meson decays (Crystal Ball results)

The Crystal Ball Collaboration has measured the semileptonic electron spectrum of B-mesons. They were produced by e+e-→-Υ(4S)→Banti B at DORIS-II. The results are: 1. Γ(B→Xueν)/Γ(B→Xceν)<7% (90%CL) where Xu(Xc) stands for hadrons containing no (a) c-quark. This result depends on the quark models for the hadronic matrix elements. 2. BR(B→Xceν)=(11.9±0.4±0.7)%. This branching ratio is model independent. 3. The results for the KM matrix elements are: vertical strokeVcbvertical stroke=0.054±0.005±0.005, model dependence <0.004. vertical strokeVub/Vcbvertical stroke<0.26 (90%CL) for the most pessimistic model. 4. The exclusive semileptonic decay B→D*eν has been identified. (orig.)