Measurement of the B semileptonic branching fraction with lepton tags

B. Barish, M. Chadha, S. Chan, G. Eigen, J. S. Miller, C. O’grady, J. Urheim, A. J. Weinstein, F. Würthwein, D. M. Asner, M. Athanas, D. W. Bliss, W. S. Brower, G. Masek, H. P. Paar, J. Gronberg, C. M. Korte, R. Kutschke, S. Menary, R. J. MorrisonS. Nakanishi, H. N. Nelson, T. K. Nelson, C. Qiao, J. D. Richman, D. Roberts, A. Ryd, H. Tajima, M. S. Witherell, R. Balest, K. Cho, W. T. Ford, M. Lohner, H. Park, P. Rankin, J. G. Smith, J. P. Alexander, C. Bebek, B. E. Berger, K. Berkelman, K. Bloom, T. E. Browder, D. G. Cassel, H. A. Cho, D. M. Coffman, D. S. Crowcroft, M. Dickson, P. S. Drell, Y. Kubota, R. Poling, CLEO Collaboration

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107 Scopus citations


We have used the CLEO II detector and 2.06fb−1 of ϒ(4S) data to measure the B-meson semileptonic branching fraction. The B → Xeν momentum spectrum was obtained over nearly the full momentum range by using charge and kinematic correlations in events with a high-momentum lepton tag and an additional electron. We find B (B → Xeν) = (10.49 ± 0.17 ± 0.43)%, with overall systematic uncertainties less than those of untagged single-lepton measurements. We use this result to calculate the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element Vcb and to set an upper limit on the fraction of ϒ(4S) decays to final states other than BB¯.

Original languageEnglish (US)
Pages (from-to)1570-1574
Number of pages5
JournalPhysical review letters
Issue number10
StatePublished - Mar 4 1996


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