ΔMs/ΔMd, sin2β and the angle γ in the presence of new ΔF=2 operators Original Research Article

We present formulae for the mass differences ΔMd and ΔMs in the B̄d,s 0–Bd,s0 systems and for the CP violation parameter ε which are valid in minimal flavour violation models giving rise to new four-fermion ΔF=2 operators. Short distance contributions to ΔMs, ΔMd and ε are parameterized by three real functions Fstt, Fdtt and Fεtt, respectively (Fstt=Fdtt=Fεtt holds only if the Standard Model (V−A)⊗(V−A) operators dominate). We present simple strategies involving the ratio ΔMs/ΔMd, sin2β and γ that allow to search for the effects of the new operators. We point out that their sizable contributions to the ratio ΔMs/ΔMd would in principle allow γ to be larger than 90°. Constraints on the functions Fitt imposed by the present (and future) experimental data are also discussed. As an example we show that for large tanβ̄≡v2/v1 and H+ not too heavy, Fstt in the MSSM with heavy sparticles can be substantially smaller than in the SM due the charged Higgs box contributions and in particular due to the growing like tan4β̄ contribution of the double penguin diagrams involving neutral Higgs boson exchanges. As a result the bounds on the function Fstt can be violated which allows to exclude large mixing of stops. In this scenario the range of sin2β following from ε and ΔMd is identical to the SM ones (0.5