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

Abstract

Evidence is presented for the baryonic $B$ meson decay $\bar{B}\to D^0\hat{I}›\bar{\hat{I}}›$ 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 $\mathcal{B}(\bar{B}\to D^0\hat{I}›\bar{\hat{I}}›)=(9.8_{-2.6}^{+2.9}\pm 1.9)\times 10^{-6}$, corresponding to a significance of $3.4$ standard deviations including systematic uncertainties. A search for the related baryonic $B$ meson decay $\bar{B}\to D^0\hat{I}{\pounds }^0\bar{\hat{I}}›$ with $\hat{I}{\pounds }^0\to \hat{I}›{\hat{I}}^3$ is performed and an upper limit $\mathcal{B}(\bar{B}\to D^0\hat{I}{\pounds }^0\bar{\hat{I}}›+\bar{B}\to D^0\hat{I}›\bar{\hat{I}}{\pounds }^0)<3.1\times 10^{-5}$ is determined at $90\%$ confidence level.

11 pages, 5 figures