Measuremént of the b baryon lifetime and branching fractions in Z decays

R. Barate, D. Buskulic, D. Decamp, P. Ghez, C. Goy, J. P. Lees, A. Lucotte, M. N. Minard, J. Y. Nief, B. Pietrzyk, M. P. Casado, M. Chmeissani, P. Comas, J. M. Crespo, M. Delfino, E. Fernandez, M. Fernandez-Bosman, Ll Garrido, A. Juste, M. MartinezG. Merino, R. Miquel, Ll M. Mir, C. Padilla, I. C. Park, A. Pascual, J. A. Perlas, I. Riu, F. Sanchez, A. Colaleo, D. Creanza, M. De Palma, G. Gelao, G. Iaselli, G. Maggi, M. Maggi, N. Marinelli, 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, R. Alemany, U. Becker, A. O. Bazarko, P. Bright-Thomas, M. Cattaneo, F. Cerutti, G. Dissertori, H. Drevermann, R. W. Forty, M. Frank, R. Hagelberg, J. B. Hansen, J. Harvey, P. Janot, B. Jost, E. Kneringer, J. Knobloch, I. Lehraus, P. Mato, A. Minten, L. Moneta, A. Pacheco, J. F. Pusztaszeri, F. Ranjard, G. Rizzo, L. Rolandi, D. Rousseau, D. Schlatter, M. Schmitt, O. Schneider, W. Tejessy, F. Teubert, I. R. Tomalin, H. Wachsmuth, A. Wagner, T. Fearnley, J. D. Hansen, J. R. Hansen, P. H. Hansen, B. S. Nilsson, B. Rensch, A. Wäänänen

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27 Citations (Scopus)


Using approximately 4 million hadronic Ζ decays recorded with the ALEPH detector from 1991 through 1995, the lifetime of the b baryon is measured with three independent methods. From the impact parameter distribution of candidate leptons in 1063 events with Λℓ- combinations, the average b baryon lifetime is measured to be 1.20 ± 0.08 ± 0.06 ps. From a sample of 193 fully reconstructed Λ+c candidates correlated with a lepton and a sample of 46 Λℓ+ℓ- combinations, the Λb lifetime is measured to be 1.21 ± 0.11 ps. The product branching fractions to these final states are Br(b → Λbb) · Br(Λb → Λℓ-v̄X) = 0.326 ± 0.016 ± 0.039% for the first sample and Br(b → Λb) · Br(Λb → Λ+cℓ-v̄X) = 0.86 ± 0.07 ± 0.14% for the second and third samples combined.
Original languageEnglish
Pages (from-to)197-211
JournalEuropean Physical Journal C
Issue number2
Publication statusPublished - 1 Dec 1998


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