We study the four-body semileptonic baryonic decay of $B^{-}\to \Lambda \overline{p}\nu \overline{\nu }$ in the standard model. We find that the decay branching ratio is $(7.9\pm 1.9)\times {10}^{-7}$. Similar to the rare decays of $B^{-}\to K^{(*)-}\nu \overline{\nu }$, this baryonic decay of $B^{-}\to \Lambda \overline{p}\nu \overline{\nu }$ is also sensitive to new physics and accessible to the future $B$ factories.

• Received 1 December 2011

DOI:https://doi.org/10.1103/PhysRevD.85.094019