Observation of the decay B[over ¯]^{0}→Λ_{c}^{+}p[over ¯]π^{0}

In a sample of 467×106 BB̅ pairs collected with the BABAR detector at the PEP-II collider at SLAC we have observed the decay B̅ 0→Λc+p̅ π0 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 Λc+→pK-π+ branching fraction, respectively. We determine an upper limit of 1.5×10-6 at 90% C.L. for the product branching fraction B(B̅ 0→Σc+(2455)p̅ )×B(Λc+→pK-π+). Furthermore, we observe an enhancement at the threshold of the invariant mass of the baryon-antibaryon pair.