We report on a new search for two-body baryonic decays of the $B$ meson. Improved sensitivity compared to previous Belle results is obtained from $414{\mathrm{fb}}^{-1}$ of data that corresponds to $449\times {10}^6$ $B\overline{B}$ pairs, which were taken on the ${\rm Y}(4\mathrm{S})$ resonance and collected with the Belle detector at the KEKB $e^{+}{e}^{-}$ collider. No significant signals are observed and we set the 90% confidence level upper limits: $\mathcal{B}(B^0\to p\overline{p})<1.1\times {10}^{-7}$, $\mathcal{B}(B^0\to \Lambda \overline{\Lambda })<3.2\times {10}^{-7}$, and $\mathcal{B}(B^{+}\to p\overline{\Lambda })<3.2\times {10}^{-7}$.

• Received 30 March 2007

DOI:https://doi.org/10.1103/PhysRevD.75.111101