Observation of the decay ¯¯¯B0→Λ+c¯pπ0

In a sample of 467 × 10 6 B ¯¯¯ B pairs collected with the BABAR detector at the PEP-II collider at SLAC we have observed the decay ¯¯¯ B 0 → Λ + c ¯ p π 0 and measured the branching fraction to be ( 1.94 ± 0.17 ± 0.14 ± 0.50 ) × 10 − 4 , where the uncertainties are statistical, systematic, and the uncertainty on the Λ + c → p K − π + branching fraction, respectively. We determine an upper limit of 1.5 × 10 − 6 at 90% C.L. for the product branching fraction B ( ¯¯¯ B 0 → Σ + c ( 2455 ) ¯ p ) × B ( Λ + c → p K − π + ) . Furthermore, we observe an enhancement at the threshold of the invariant mass of the baryon-antibaryon pair