Constraints on Strong Dynamics from Rare B and K Decays

We discuss the constraints from rare B and K decays on the Electroweak Symmetry Breaking (EWSB) sector, as well as on theories of fermion masses. We focus on models involving new strong dynamics and show that transitions involving Flavor Changing Neutral Currents (FCNC) play an important role in disentangling the physics in these scenarios. In a model-independent approach to the EWSB sector, the information from rare decays is complementary to precision electroweak observables in bounding the contributions to the effective lagrangian. We compare the pattern of deviations from the standard model that results from these sources, with the deviations associated with the mechanism for generating fermion masses.