We report results of a search for the charmless two-body baryonic decays $B^0\to p\overline{p}$, $B^0\to \Lambda \overline{\Lambda }$, and $B^{+}\to p\overline{\Lambda }$ based on the analysis of a $140{\mathrm{fb}}^{-1}$ data sample. We set 90% confidence level upper limits on their branching fractions: $\mathcal{B}(B^0\to p\overline{p})<4.1\times {10}^{-7}$, $\mathcal{B}(B^0\to \Lambda \overline{\Lambda })<6.9\times {10}^{-7}$, and $\mathcal{B}(B^{+}\to p\overline{\Lambda })<4.9\times {10}^{-7}$.

• Received 28 February 2005

DOI:https://doi.org/10.1103/PhysRevD.71.072007