Model-independent constraints on Delta F=2 operators and the scale of New Physics

Abstract

We update the constraints on new-physics contributions to Delta F=2 processes from the generalized unitarity triangle analysis, including the most recent experimental developments. Based on these constraints, we derive upper bounds on the coefficients of the most general Delta F=2 effective Hamiltonian. These upper bounds can be translated into lower bounds on the scale of new physics that contributes to these low-energy effective interactions. We point out that, due to the enhancement in the renormalization group evolution and in the matrix elements, the coefficients of non-standard operators are much more constrained than the coefficient of the operator present in the Standard Model. Therefore, the scale of new physics in models that generate new Delta F=2 operators, such as next-to-minimal flavour violation, has to be much higher than the scale of minimal flavour violation, and it most probably lies beyond the reach of direct searches at the LHC.

32 pages, 11 figures, 6 tables. v2: error in the implementation of D0 untagged Bs->J/Psi phi correlation matrix corrected. Improved presentation of the results and discussion of ambiguities in untagged Bs->J/Psi phi. Results for NP in Bs oscillations changed. Final version to appear in JHEP