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Measurements of |V(cb)|, form-factors and branching fractions in the decays anti-B0 ---> D*+ lepton- anti-lepton-neutrino and anti-B0 ---> D+ lepton- anti-lepton-neutrino

Research output: Contribution to journalJournal article


  • ALEPH Collaboration
<mark>Journal publication date</mark>1997
<mark>Journal</mark>Physics Letters B
Issue number3-4
Number of pages15
Pages (from-to)373-387
<mark>Original language</mark>English


Two samples of exclusive semileptonic decays, 579 events and 261 events, are selected from approximately 3.9 million hadronic Z decays collected by the ALEPH detector at LEP. From the reconstructed differential decay rate of each sample, the product of the hadronic form factor (ω) at zero recoil of the D(∗)+ meson and the CKM matrix element |Vcb| are measured to be , FD+(1)|Vcb| = (27.8 ± 6.8stat ± 6.5syst) × 10−3. The ratio of the form factors FD+(1) and is measured to be . A value of |Vcb| is extracted from the two samples, using theoretical constraints on the slope and curvature of the hadronic form factors and their normalization at zero recoil, with the result |Vcb| = (34.4 ± 1.6stat ± 2.3syst ± 1.4th) × 10−3. The branching fractions are measured from the two integrated spectra to be %, %.