Evidence for B+ --> Jpsi p Lambda-bar and Search for B0 --> Jpsi p p-bar

Abstract

We have performed a search for the decays $B^+\to J/\psi p \bar{\Lambda}$ and $B^0\to J/psi p \bar{p}$ in a data set of $(88.9 \pm 1.0)\times 10^6$ $\Upsilon(4S)$ decays collected by the BaBar experiment at the PEP-II $\e^+e^-$ storage ring at the Stanford Linear Accelerator Center. Four charged $B$ candidates have been observed with an expected background of $0.21\pm 0.14$ events. The corresponding branching fraction is $12^{+9}_{-6}\times 10^{-6}$, where statistical and systematic uncertainties have been combined. The result can be interpreted as a 90% confidence level (CL) upper limit of $26 \times 10^{-6}$. We also find one $B^0$ candidate, with an expected background of $0.64\pm 0.17$ events, implying a 90% CL upper limit of $1.9 \times 10^{-6}$.