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

TL;DR

This paper examines the role of final state interactions in B meson decays, specifically analyzing the impact of different meson exchanges on the $B o \pi K$ decay process, and finds that certain expected enhancements are not observed.

Contribution

It provides a detailed discussion on the significance of D* and D** exchanges in B decay final state interactions, challenging previous assumptions about their impact.

Findings

$\pi$--exchange rescatterings are not significant.

D* and D** exchanges could enhance $ o \pi K$ decay rates.

Estimated enhancements do not match large observed increases.

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 $D^*$ 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 $B\to \pi K$ branching ratio significantly. However our estimates fail to predict a large enhancement.