Observation of B- -> pbar Lambda D0 at Belle

We study B- meson decays to (p) over bar Lambda D-(*)0 final states using a sample of 657 x 10(6) B (B) over bar events collected at the Gamma(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. The observed branching fraction for B- -> (p) over bar Lambda D-0 is (1.43(-0.25)(+0.28) +/-0.18) x 10(-5) with a significance of 8.1 standard deviations, where the uncertainties are statistical and systematic, respectively. Most of the signal events have the (p) over bar Lambda mass peaking near threshold. No significant signal is observed for B- -> (p) over bar Lambda D-0 and the corresponding upper limit on the branching fraction is 4.8 x 10(-5) at the 90% confidence level.