Evidence for the Baryonic Decay B̅→ D⁰ΛΛ̅

Evidence is presented for the baryonic B meson decay B̅⁰ → D⁰ΛΛ̅ based on a data sample of 471 x 10⁶ BB̅ pairs collected with the BABAR detector at the PEP-II asymmetric e⁺e⁻ collider located at the SLAC National Accelerator Laboratory. The branching fraction is determined to beℬ(B̅⁰ → D⁰ΛΛ̅) = (9.8_{-2.6}^{+2.9} ± 1.9) x 10⁻⁶, corresponding to a significance of 3.4 standard deviations including additive systematic uncertainties. A search for the related baryonic B meson decay B̅⁰ → D⁰Σ⁰Λ̅ with Σ⁰ → Λγ is performed and an upper limit ℬ(B̅⁰ → D⁰Σ⁰Λ̅ + B̅⁰ → D⁰ΛΣ̅⁰ < 3.1 x 10⁻⁵ is determined at 90% confidence level.