Implications of large dimuon CP asymmetry in Bd,s decays on minimal flavor violation with low tan β

The D0 collaboration has recently announced evidence for a dimuon CP asymmetry in Bd,s decays of order one percent. If confirmed, this asymmetry requires new physics. We argue that for minimally flavor violating (MFV) new physics, and at low tan β = vu/vd, there are only two four-quark operators (Q2,3) that can provide the required CP violating effect. The scale of such new physics must lie below 260 GeV $ \sqrt {{\tan \beta }} $. The effect is universal in the Bs and Bd systems, leading to SψK ∼ sin 2β − 0.15 and Sψϕ ∼ 0.25. The effects on ϵK and on electric dipole moments are negligible. The most plausible mechanism is tree-level scalar exchange. MFV supersymmetry with low tan β will be excluded. Finally, we explain how a pattern of deviations from the Standard Model predictions for Sψϕ, SψK and ϵK can be used to test MFV and, if MFV holds, to probe its structure in detail.