content_image/340210.jpg content_image/340211.jpg content_image/340212.jpg
energy processes can still be established implementing specific symmetry properties, such as the MFV hypothesis (Sect. IV). The experimental tests of such correlations allow us to test/establish general features of the new theory which holds independently of the dynamical details of the model. In particular, B , D and K decays are extremely useful in determining the flavor-symmetry breaking pattern of the NP model. 

## A. Bounds from Δ F = 2 down-type transitions 

The starting points for this analysis is the observation that in several realistic NP models we can neglect non-standard effects in all cases where the corresponding effective operator is gen- erated at the tree-level within the SM. This general assumption implies that the experimental determination of the CKM matrix via tree-level processes is free from the contamination of NP contributions. Using this determination we can unambiguously predict meson-antimeson mixing and FCNC amplitudes within the SM and compare it with data, constraining the couplings of the Δ F = 2 operators in (3.1). Each Δ F = 2 amplitude is then conveniently parametrized in terms of the shift induced in the modulo and the CPV phase, or the real and imaginary part [10, 11]: 

<img src='content_image/340210.jpg'>

An updated analysis of these constraints has been presented in [12] (see Fig. 2). The main conclu- sions that can be drawn from this analysis can be summarized as follows: 

(i) In all the three accessible short-distance amplitudes ( K $^{0}$– K $^{0}$, B$_{d}$ – B$_{d}$ , and B$_{s}$ – B$_{s}$ ) the mag- nitude of the new-physics amplitude cannot exceed, in size, the SM short-distance contribution. The latter is suppressed by both the GIM mechanism and the hierarchical structure of the CKM matrix, 

<img src='content_image/340211.jpg'>

where F is a loop function of O (1). As a result, new-physics models with TeV-scale flavored degrees of freedom and O (1) effective flavor-mixing couplings are ruled out. To set explicit bounds, let us consider for instance the subset of left-handed Δ F = 2 operators in the generic effective Lagrangian in (3.1), namely 

<img src='content_image/340212.jpg'>

