B meson decays to baryons in the diquark model

We study B meson decays to two charmless baryons in the diquark model, including strong and electroweak penguins as well as the tree operators. It is shown that penguin operators can enhance $\bar{B} \to \Bb_s \bar{\Bb}$ considerably, but affect $\bar{B} \to \Bb_1 \bar{\Bb}_2$ only slightly, where $\Bb_{(1,2)}$ and $\Bb_s$ are non-strange and strange baryons, respectively. The $\gamma$ dependence of the decay rates due to tree-penguin interference is illustrated. In principle, some of the $\Bb_s \bar{\Bb}$ modes could dominate over $\Bb_1 \bar{\Bb}_2$ for $\gamma > 90^\circ$, but in general the effect is milder than their mesonic counterparts. This is because the $O_6$ operator can only produce vector but not scalar diquarks, while the opposite is true for $O_1$ and $O_4$. Predictions from diquark model are compared to those from the sum rule calculation. The decays $\bar{B} \to \Bb_s \bar{\Bb}_s$ and inclusive baryonic decays are also discussed.