Possibility of Large Final State Interaction Phases in Light of B \to K\pi and \pi\pi Data

Abstract

The newly observed $\bar B^0 \to \bar K^0\pi^0$ mode is quite sizable while $\pi^-\pi^+$ is rather small. Data also hint at $\pi^-\pi^0 \gtrsim \pi^-\pi^+$. Though consistent with zero, central values of CP violating asymmetries in $K^-\pi^{+,0}$ and $\bar K^0\pi^-$ show an interesting pattern. Taking cue from these, we suggest that, besides $\gamma\equiv {\rm arg} (V_{ub}^*)$ being large, the rescattering phase $\delta$ in $K\pi$ and $\pi\pi$ modes may be greater than $90^\circ$. If this is true, not only the above trends can be accounted for, one would also find $\pi^0\pi^0 \sim \pi^-\pi^{+,0}$, and the CP asymmetry in $\bar B^0$ vs. $B^0 \to \pi^-\pi^+$ could be as large as -60%. These results can be tested in a couple of years.