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of new physics not far from the TeV region. These bounds are very similar to the bounds on flavor-conserving operators derived by precision electroweak tests. This observation reinforces the conclusion that a deeper study of rare decays is definitely needed in order to clarify the flavor problem: the experimental precision on the clean FCNC observables required to obtain bounds more stringent than those derived from precision electroweak tests (and possibly discover new physics) is typically in the 1% − 10% range. 

Although MFV seems to be a natural solution to the flavor problem, it should be stressed that (i) this is not a theory of flavor (there is no explanation for the observed hierarchical structure of the Yukawas), and (ii) we are still far from having proved the validity of this hypothesis from data (in the effective theory language we can say that there is still room for sizable new sources of flavor symmetry breaking beside the SM Yukawa couplings [28]). A proof of the MFV hypothesis can be achieved only with a positive evidence of physics beyond the SM exhibiting the flavor-universality pattern (same relative correction in s → d , b → d , and b → s transitions of the same type) predicted by the MFV assumption. While this goal is quite difficult to be achieved, the MFV framework is quite predictive and thus could easily be falsified: in Table III we list some clean MFV predictions which could be falsified by future experiments. Violations of these bounds would not only imply physics beyond the SM, but also a clear signal of new sources of flavor symmetry breaking beyond the Yukawa couplings. 

The idea that the CKM matrix rules the strength of FCNC transitions also beyond the SM has become a very popular concept in recent literature and has been implemented and discussed in several works. It is worth stressing that the CKM matrix represents only one part of the problem: a key role in determining the structure of FCNCs is also played by quark masses, or by 

