A Study of (bar B) → Ξ_cΛ_c^- and (bar B) → Λ_c⁺Λ_c^-(bar K) Decays at BABAR

We report measurements of B-meson decays into two- and three-body final states containing two charmed baryons using a sample of 230 million Υ(4S) → B(bar B) decays. We find significant signals in two modes, measuring branching fractions β(B^- → Λ_c⁺Λ_c^-K^-) (1.14 ± 0.15 ± 0.17 ± 0.60) x 10^-3 and β(B^-→ Ξ⁰_c(bar Λ)_c^-) x β(Ξ⁰_c → Ξ^-π⁺) = (2.08 ± 0.65 ± 0.29 ± 0.54) x 10^-5, where the uncertainties are statistical, systematic, and from the branching fraction β(Λ⁺_c → pK^-π⁺), respectively. We also set upper limits at the 90% confidence level on two other modes: β((bar β)⁰ → Ξ⁺_c(bar Λ)^-_c) x β(Ξ⁺_c → Ξ^-π⁺π⁺) < 5.6 x 10^-5 and β((bar B)⁰ → Λ⁺_c(bar Λ)^-_c(bar K)⁰) < 1.5 x 10^-3. We observe structure centered at an invariant mass of 2.93 GeV/c² in the Λ⁺_cK^- mass distribution of the decay B^- → Λ⁺_c(bar Λ)^-_cK^-