The Role of $B_s\to K\pi$ in Determining the Weak Phase $\gamma$

The decay rates for $B^0\to K^{+}{\pi }^{-}$, $B^{+}\to K^0{\pi }^{+}$, and the charge-conjugate processes were found to provide information on the weak phase $\gamma \equiv \mathrm{A}\mathrm{r}\mathrm{g}(V_{ub}^{\ast })$ when the ratio $r$ of weak tree and penguin amplitudes was taken from data on $B\to \pi \pi$ or semileptonic $B\to \pi$ decays. We show here that the rates for $B_s\to K^{-}{\pi }^{+}$ and $\bar B_s \to K^+ \pi^-$canprovidethenecessaryinformationon$r$, and estimate the statistical accuracy of forthcoming measurements at the Fermilab Tevatron.