Observation of the baryonic B decay ¯¯¯B0→Λ+c¯¯¯ΛK−

Abstract

We report the observation of the baryonic B decay ¯¯¯ B 0 → Λ + c ¯¯¯ Λ K − with a significance larger than 7 standard deviations based on 471 × 10 6 B ¯¯¯ B pairs collected with the BABAR detector at the PEP-II storage ring at SLAC. We measure the branching fraction for the decay ¯¯¯ B 0 → Λ + c ¯¯¯ Λ K − to be ( 3.8 ± 0.8 stat ± 0.2 sys ± 1.0 Λ + c ) × 10 − 5 . The uncertainties are statistical, systematic, and due to the uncertainty in the Λ + c branching fraction. We find that the Λ + c K − invariant-mass distribution shows an enhancement above 3.5 GeV / c 2 .