Evidence for the baryonic decay B0bar --> D0 Lambda Lambdabar

Abstract

Evidence is presented for the baryonic $B$ meson decay $\bar{B}\rightarrow D^0 Λ\barΛ$ based on a data sample of $471 \times 10^6$ $B\bar{B}$ pairs collected with the {\it BABAR} detector at the PEP2 asymmetric $e^+e^-$ collider located at the SLAC National Accelerator Laboratory. The branching fraction is determined to be $\mathcal{B}(\bar{B}\rightarrow D^0 Λ\barΛ) = (9.8^{+2.9}_{-2.6} \pm 1.9)\times 10^{-6}$, corresponding to a significance of $3.4$ standard deviations including systematic uncertainties. A search for the related baryonic $B$ meson decay $\bar{B}\rightarrow D^0 Σ^0 \barΛ$ with $Σ^0\rightarrowΛγ$ is performed and an upper limit $\mathcal{B}(\bar{B}\rightarrow D^0 Σ^0 \barΛ + \bar{B}\rightarrow D^0 Λ\barΣ^0) < 3.1 \times 10^{-5}$ is determined at $90\%$ confidence level.

11 pages, 5 figures