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

Abstract

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

5 pages, use elsart.sty; The previous version is erroneous in explaining the "charm peguin" effects. No large enhancement to $B\to πK$ is found through $D^+D_s^-$ intermediate state