Searching for New Physics in Non-Leptonic B Decays

We present the allowed regions in the space of observables of certain non-leptonic B-meson decays into two light pseudoscalar mesons, which are implied by the Standard-Model expressions for the corresponding transition amplitudes. A future measurement of observables not lying within these regions would immediately indicate the presence of new physics. We give the range for $B\to\pi K$ decays, and for the system of $B_d\to\pi^+\pi^-$, $B_s\to K^+K^-$ decay modes. This approach tells us how much space is left for new physics, showing explicitly the region of observables that can only be explained by new physics. If the measured observables lie within the range implied by the Standard Model, we may extract values for the CKM angle $\gamma$. Comparing these with values obtained from other strategies we may well encounter discrepancies that could also signal new physics.