FIG. 1: Allowed region in the ρ, η plane. Superimposed are the individual constraints from charmless semileptonic B decays ( | V$_{ub}$/V$_{cb}$ | ), mass differences in the B 0 (Δ m$_{d}$ ) and B$_{s}$ (Δ m$_{s}$ ) neutral meson systems, and CP violation in K → ππ ( ε$_{K}$ ), B → ψK (sin 2 β ), B → ππ, ρπ, ρρ ( α ), and B → DK ( γ ). Taken from [6]. follow this approach in Sect. V and VI in two well-motivated SM extensions. In this and the next section we follow the second strategy, which is less predictive but also more general. Assuming the new degrees to be heavier than SM fields, we can integrate them out and describe NP effects by means of a generalization of the Fermi Theory. The SM Lagrangian becomes the renormalizable part of a more general local Lagrangian which includes an infinite tower of operators with dimension d > 4, constructed in terms of SM fields, suppressed by inverse powers of an effective scale Λ > M$_{W}$ : This general bottom-up approach allows us to analyse all realistic extensions of the SM in terms of a limited number of parameters (the coefficients of the higher-dimensional operators). The drawback of this method is the impossibility to establish correlations of NP effects at low and high energies: the scale Λ defines the cut-off of the effective theory. However, correlations among different low- L eff = L SM + ∑ c ( d ) i Λ ( d − 4) O ( d ) i (SM fields) . (3.1) 6 d m K K s m  &  d m SL ub V ub V sin 2 (excl. at CL > 0.95)  < 0 sol. w/ cos 2 excluded at CL > 0.95 −1.0 −0.5 0.0 0.5 1.0 1.5 2.0 −1.5 −1.0 −0.5 0.0 0.5 1.0 1.5 excluded area has CL > 0.95 Moriond 09 C K M$_{i t t e r}$