Testing the standard model with B_s⁰→K⁺K^- decays

In the limit of flavor SU(3) symmetry, the amplitudes for B_d⁰→π⁺π^- and B_s⁰→K⁺K^- are related to one another. Taking the values of the weak phases β and γ from independent measurements, the ratio R_d^s≡BR(B_s⁰→K⁺K^-)/BR(B_d⁰→π⁺π^-) and the two B_d⁰→π⁺π^- CP asymmetries A_dir and A_mix depend on only two quantities. By measuring these three observables, one can test for the presence of physics beyond the standard model. In this paper, using present data, and including theoretical uncertainties due to SU(3) breaking, we perform such an analysis. The experimental errors are still very large, but with improved measurements from Babar, Belle and CDF this will be a useful method to search for new physics.