Observation of the Λ0b → J/ψpπ decay

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

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The first observation of the Cabibbo-suppressed decay Λ0b → J/ψpπ is reported using a data sample of proton-proton collisions at 7 and 8 TeV, corresponding
to an integrated luminosity of 3 fb−1. A prominent signal is observed and the branching
fraction relative to the decay mode Λ0b → J/ψpK is determined to be
B(Λ0b → J/ψpπ) / B(Λ0b → J/ψpK)
= 0.0824 ± 0.0025 (stat) ± 0.0042 (syst). 
A search for direct CP violation is performed. The difference in the CP asymmetries between these two decays is found to be
ACP0b → J/ψpπ) − ACP0b → J/ψpK) = (+5.7 ± 2.4 (stat) ± 1.2 (syst))%, which is compatible with CP symmetry at the 2.2σ level.
Original languageEnglish
Article number103
Number of pages18
JournalJournal of High Energy Physics
Issue number7
Publication statusPublished - 22 Jul 2014


  • B physics
  • CP violation
  • Branching fraction
  • Flavor physics
  • Hadron-Hadron Scattering


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