Searches for Λ0b and Ξ0b decays to K0s- and K0spK- final states with first observation of the Λ0b → K0s- decay

LHCb Collaboration, R. Aaij, B. Adeva, M. Adinolfi, A. Affolder, Z. Ajaltouni, J. Albrecht, F. Alessio, M. Alexander, S. Ali, G. Alkhazov, P. Alvarez Cartelle, A. A. Alves, S. Amato, S. Amerio, Y. Amhis, L. Anderlini, J. Anderson, R. Andreassen, M. AndreottiJ. E. Andrews, R. B. Appleby, O. Aquines Gutierrez, F. Archilli, A. Artamonov, M. Artuso, E. Aslanides, G. Auriemma, M. Baalouch, S. Bachmann, J. J. Back, A. Badalov, V. Balagura, W. Baldini, R. J. Barlow, C. Barschel, S. Barsuk, W. Barter, V. Batozskaya, Th Bauer, S. Bifani, P. Griffith, P. Ilten, I. R. Kenyon, C. Lazzeroni, A. Mazurov, J. McCarthy, C. J. Parkinson, L. Pescatore, D. Popov, N. K. Watson

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A search for previously unobserved decays of beauty baryons to the final states K0s- and K0spK- is reported. The analysis is based on a data sample corresponding to an integrated luminosity of 1.0 fb-1 of pp collisions. The Λ0b → K-0- decay is observed with a significance of 8.6σ, with branching fraction B(Λ0b → K-0) = (1.26 ± 0.19 ± 0.09 ± 0.34 ± 0.05) × 10−5, where the uncertainties are statistical, systematic, from the ratio of fragmentation fractions f Λ0b/fd, and from the branching fraction of the B0 → K0π+π- normalisation channel, respectively. A first measurement is made of the CP asymmetry, giving ACP0b → K-0) = 0.22 ± 0.13 (stat) ± 0.03 (syst). No significant signals are seen for Λ0b → K0spK- decays, Ξ0b decays to both the K0s- and K0spK- final states, and the Λ0b → D-s(→ K0sK-)p decay, and upper limits on their branching fractions are reported.

Original languageEnglish
Article number87
Number of pages24
JournalJournal of High Energy Physics
Issue number4
Publication statusPublished - 11 Apr 2014


  • B physics
  • Branching fraction
  • Flavor physics
  • Hadron-hadron scattering

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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