Charmless exclusive baryonicBdecays

We present a systematical study of two-body and three-body charmless baryonic B decays. The branching ratios for two-body modes are in general very small, typically less than ${10}^{-6},$ except that $\mathcal{B}{(B}^{-}\to p{\overline{\Delta }}^{--})\sim 1\times {10}^{-6}.$ In general, $\overline{B}\to N\overline{\Delta }>\overline{B}\to N\overline{N}$ due to the large coupling constant for ${\Sigma }_b\to B\Delta .$ For three-body modes we focus on octet baryon final states. The leading three-dominated modes are $B^0\to p\mathrm{n̄}{\pi }^{-}\left({\rho }^{-}\right),$ $n\overline{p}{\pi }^{+}\left({\rho }^{+}\right)$ with a branching ratio of order $3\times {10}^{-6}$ for $B^0\to p\mathrm{n̄}{\pi }^{-}$ and $8\times {10}^{-6}$ for $B^0\to p\mathrm{n̄}{\rho }^{-}.$ The penguin-dominated decays with strangeness in the meson, e.g., $B^{-}\to p\overline{p}{K}^{-\left(*\right)}$ and $B^0\to p\mathrm{n̄}{K}^{-\left(*\right)},$ $n\mathrm{n̄}{K}^{0\left(*\right)},$ have appreciable rates and the $N\overline{N}$ mass spectrum peaks at low mass. The penguin-dominated modes containing a strange baryon, e.g., $B^0\to {\Sigma }^0\overline{p}{\pi }^{+},$ ${\Sigma }^{-}\mathrm{n̄}{\pi }^{+},$ have branching ratios of the order of $(1\mathrm{}–4)\times {10}^{-6}.$ In contrast, the decay rate of $B^0\to \Lambda \overline{p}{\pi }^{+}$ is smaller. We explain why some of the charmless three-body final states in which baryon-antibaryon pair production is accompanied by a meson have a larger rate than their two-body...