Understanding $B\to D^{\ast -}N\bar{N}$ and Its Implications

The CLEO Collaboration recently reported the observation of the $B^0\to D^{-}p\bar{n}$modeatarateonlyafactorof4--5lowerthan$B^0\to D^{-}\rho^+$and$D^{*-}\pi^+$. We try to understand this with a factorization approach of current produced nucleon pairs. The baryon weak vector current form factors are related by isospin rotation to nucleon electromagnetic form factors. By using $G_M^{p,n}$ measured from $e^{+}{e}^{-}\to \bar{N}N$ and $p\bar{p}\to e^{+}{e}^{-}$ processes, assuming factorization of the $B^0\to D^{\ast -}$ transition and the $p\bar{n}$ pair production, we are able to account for up to 60% of the observed rate. The remainder is argued to arise from the axial current. The model is then applied to B decays to other mesons plus $p\bar{n}$ modes and $D^{\ast -}$ plus strange baryon pairs.