Some Remarks on the Final State Interactions in $B\to \pi K$ Decays

Abstract

Careful discussions are made on some points which are met in studying B decay final state interactions, taking the $B^0\to {\pi }^{+}{K}^{-}$ process as an example. We point out that $\pi$--exchange rescatterings are not important, whereas for $D^{\ast }$ and $D^{\ast \ast }$ exchanges, since the $B^0\to D^{+}{D}_s^{-}$ decay has a large branching ratio their contributions may be large enough to enhance the $B\to \pi K$ branching ratio significantly. However our estimates fail to predict a large enhancement.

Comments: 5 pages, use elsart.sty; The previous version is erroneous in explaining the "charm peguin" effects. No large enhancement to $B\to \pi K$ is found through $D^{+}{D}_s^{-}$ intermediate state