Electroweak Penguins, Final State Interaction Phases and CP Violatioin in $B\to K \pi$ Decays

Abstract

The recently observed $B^-\to K^- \pi^0$, $\bar K^0 \pi^-$ and $\bar B^0 \to K^- \pi^+$ decay modes appear to have nearly equal branching ratios. This suggests that tree and electroweak penguins play an important role, and inclusion of the latter improves agreement between factorization calculation and experimental data. The value $\gamma$ in the range $90^\circle - 130^\circle$ and $220^\circle - 260^\circle$ is favored, while the $\bar B^0 \to \bar K^0 \pi^0$ rate is suppressed. Direct CP violation for $B\to K \pi$ modes can be large if final state interaction phases are large.