Observation of the baryonic B-decay B¯0→Λc+p¯K-π+

We report the observation of the baryonic B-decay B̅ 0→Λc+p̅ K-π+, excluding contributions from the decay B̅ 0→Λc+Λ̅ K-. Using a data sample of 467×106 BB̅ pairs collected with the BABAR detector at the PEP-II storage ring at SLAC, the measured branching fraction is (4.33±0.82stat±0.33syst±1.13Λc+)×10-5. In addition we find evidence for the resonant decay B̅ 0→Σc(2455)++p̅ K- and determine its branching fraction to be (1.11±0.30stat±0.09syst±0.29Λc+)×10-5. The errors are statistical, systematic, and due to the uncertainty in the Λc+ branching fraction. For the resonant decay B̅ 0→Λc+p̅ K̅ *0 we obtain an upper limit of 2.42×10-5 at 90% confidence level.