Search for (B)over-bar0→Λc+(Λ)over-barc- decay at Belle

We search for the doubly charmed baryonic decay (B) over bar (0) Lambda(+)(c)(Lambda) over bar (-)(c), in a data sample of 520 x 10(6) B (B) over bar events accumulated at the Gamma(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+) e(-) collider. We find no significant signal and set an upper limit of B((B) over bar (0) -> Lambda(+)(c)(Lambda) over bar (-)(c)) < 6.2 x 10(-5) at 90% confidence level. The result is significantly below a naive extrapolation from B B(<(B)over bar> -> Xi(0)(c)(Lambda) over bar (-)(c) assuming a simple Cabibbo-suppression factor of vertical bar V-cd/V-cs vertical bar(2). The small branching fraction may be attributed to a suppression due to the large momentum of the baryonic decay products, which has been observed in other charmed baryonic two-body B decays.