Three-Body Charmful Baryonic B Decays $\bar{B}\to D(D^{\ast })N\bar{N}$

We study the charmful three-body baryonic B decays $\bar B\to D^{()}N\bar N$:thecolor-allowedmodes$\bar B^0\to D^{()+}n\bar p$ and the color-suppressed ones ${\bar{B}}^0\to D^{(\ast )0}p\bar{p}$. While the $D^{\ast +}\mathrm{/}{D}^{+}$ production ratio is predicted to be of order 3, it is found that $D^{0}p\bar{p}$ has a similar rate as $D^{\ast 0}p\bar{p}$. It is pointed out that $\bar B^0\to D(D^*)N\bar N$ are dominated by the nucleon vector current or by vector meson intermediate states, whereas ${\bar{B}}^0\to D^{0}p\bar{p}$ proceeds mainly via the exchange of the axial-vector intermediate state $a_1(1260)$. The study of the $N\bar{N}$ invariant mass distribution in general indicates a threshold baryon pair production; that is, a recoil charmed meson accompanied by a low mass baryon pair except that the spectrum of $D^{0}p\bar{p}$ has a hump at large $p\bar p$invariantmass$m_{p\bar p}\sim 3.0$ GeV.