The persistent tensions between inclusive and exclusive determinations of |Vcb| and |Vub| weaken
the power of theoretically clean rare K and B decays in the search for new physics (NP). We
demonstrate how this uncertainty can be practically removed by considering within the SM suit-
able ratios of various branching ratios. This includes the branching ratios for K+ → π+ν ̄ν,
KL → π0ν ̄ν, KS → μ+ μ−, Bs,d → μ+ μ− and B → K(K∗)ν ̄ν. Also εK , ∆Md , ∆Ms and the mixing
induced CP-asymmetry SψKS , all measured already very precisely, play an important role in this
analysis. The highlights of our analysis are 16 |Vcb| and |Vub| independent ratios that often are
independent of the CKM parameters or depend only on the angles β and γ in the Unitarity Tri-
angle with β already precisely known and γ to be measured precisely in the coming years by the
LHCb and Belle II colaborations. Once γ is measured precisely these 16 ratios taken together are
expected to be a powerful tool in the search for new physics. On the other hand within the SM
they imply that to obtain the SM predictions for rare Kaon decays only the experimental values of
|εK | and SψKS are needed. In particular we find: B(K+ → π+ν ̄ν)SM = (8.60 ± 0.42) × 10−11 and
B(KL → π0ν ̄ν)SM = (2.94 ± 0.15) × 10−11. This are the most precise determinations to date.
Similarly, to obtain the SM predictions for all rare B decay branching ratios only the knowledge
of the experimental values of ∆Ms,d is required.