Hadronic Rare $B$ Decays via Exchange or Annihilation Diagrams

Abstract

The two-body mesonic $B$ decays induced only via a single $W$-exchange or annihilation quark diagram, such as $B_u^{-}\to D_s^{(\ast )-}{K}^{(\ast )0}$ and ${\bar{B}}_d^0\to D_s^{(\ast )+}{K}^{(\ast )-}$, are analyzed in the factorization approximation. We estimate the branching ratios for those transitions into two pseudoscalar mesons, and find them to be negligibly small. The significant effect of final-state rescattering is illustrated by taking $B_u^{-}\to D^{-}{\bar{K}}^0$ for example.

Comments: Postscript 8 pages. (P.R.D, in press)