Searching for New Physics in the b->d FCNC using B_s⁰(t)->φ K_s and B_d⁰(t)->K⁰bar{K}⁰

Time-dependent measurements of the decays B_s^0(t)-->\phi K_s and B_d^0(t) --> K^0 \bar{K}^0 can be used to compare the weak phases of B_d^0-\bar{B}_d^0 mixing and the t-quark contribution to the b->d penguin. Since these two phases are equal in the standard model, any discrepancy would be a sign of new physics, specifically in the b->d flavour-changing neutral current (FCNC). The method can be applied to other pairs of decays, such as B_s^0(t)--> J/\Psi K_s and B_d^0(t)--> J/\Psi \pi^0.