Searching for new physics in the b→d FCNC using Bs0(t)→φKS and Bd0(t)→K0K0

Time-dependent measurements of the decays Bs0(t)→φKS and Bd0(t)→K0K0 can be used to compare the weak phases of Bd0–Bd0 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 Bs0(t)→J/ΨKS and Bd0(t)→J/Ψπ0.