Observation of B+→Ξc0Λc+ and evidence for B0→Ξc-Λc+

We report the first observation of the decay B+→Ξc0Λc+ with a significance of 8.7σ and evidence for the decay B0→Ξc-Λc+ with a significance of 3.8σ. The product B(B+→Ξc0Λc+)xB(Ξc0→Ξ+π-) is measured to be (4.8-0.9+1.0±1.1±1.2)x10-5, and B(B0→Ξc-Λc+)xB(Ξc-→Ξ+π-π-) is measured to be (9.3-2.8+3.7±1.9±2.4)x10-5. The errors are statistical, systematic and the error of the Λc+→pK-π+ branching fraction, respectively. The decay B+→Ξc0Λc+ is the first example of a two-body exclusive B+ decay into two charmed baryons. The data used for this analysis was accumulated at the Υ(4S) resonance, using the Belle detector at the e+e- asymmetric-energy collider KEKB. The integrated luminosity of the data sample is equal to 357 fb-1, corresponding to 386x106 BB pairs