Determination of |V(ub)|/|V(cb)| with DELPHI at LEP

Christopher Parkes, R. Barate, D. Decamp, P. Ghez, C. Goy, S. Jezequel, J. P. Lees, F. Martin, E. Merle, M. N. Minard, B. Pietrzyk, R. Alemany, S. Bravo, M. P. Casado, M. Chmeissani, J. M. Crespo, E. Fernandez, M. Fernandez-Bosman, Ll Garrido, E. GraugésA. Juste, M. Martinez, G. Merino, R. Miquel, Ll M. Mir, P. Morawitz, A. Pacheco, I. Riu, H. Ruiz, A. Colaleo, D. Creanza, M. De Palma, G. Iaselli, G. Maggi, M. Maggi, S. Nuzzo, A. Ranieri, G. Raso, F. Ruggieri, G. Selvaggi, L. Silvestris, P. Tempesta, A. Tricomi, G. Zito, X. Huang, J. Lin, Q. Ouyang, T. Wang, Y. Xie, R. Xu, S. Xue, J. Zhang, L. Zhang, W. Zhao, D. Abbaneo, G. Boix, O. Buchmüller, M. Cattaneo, F. Cerutti, V. Ciulli

    Research output: Contribution to journalArticlepeer-review


    The ratio of the CKM quark-mixing matrix elements |V(ub)|/|V(cb)| has been measured using B hadron semileptonic decays. The analysis uses the reconstructed mass M(x) of the secondary hadronic system produced in association with an identified lepton. Since B → X(u)lv̄ transitions are characterised by hadronic masses below those of the D mesons produced in B → X(c)lv̄ transitions, events with a reconstructed value of M(x) significantly below the D mass are selected. Further signal enrichments are obtained using the topology of reconstructed decays and hadron identification. A fit to the numbers of decays in the b → u enriched and depleted samples with M(x) above and below 1.6 GeV/c2 and to the shapes of the lepton energy distribution in the B rest frame gives |V(ub)|/|V(cb)| = 0.103 (-0.012)/(+0.011)(stat.) ± 0.016(syst.) ± 0.010(model) and, correspondingly, a charmless semileptonic B decay branching fraction of BR(B → X(u)lv̄= (1.57 ± 0.35 (stat.) ± 0.48 (syst.) ± 0.27 (model)) x 10-3. (C) 2000 Published by Elsevier Science B.V.
    Original languageEnglish
    Pages (from-to)14-30
    Number of pages16
    JournalPhysics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics
    Issue number1-3
    Publication statusPublished - 6 Apr 2000


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