Rare decays and CP violation beyond the Standard Model

We review the status of rare decays and CP violation in extensions of the Standard Model. We analyze the determination of the unitarity triangle and the model-independent constraints on new physics that can be derived from this analysis. We find stringent bounds on new contributions to K-Kbar and Bd-Bdbar mixing, pointing either to models of minimal flavour violation or to models with new sources of flavour and CP violation in b to s transitions. We discuss the status of the universal unitarity triangle in minimal flavour violation, and study rare decays in this class of models. We then turn to supersymmetric models with nontrivial mixing between second and third generation squarks, discuss the present constraints on this mixing and analyze the possible effects on CP violation in b to s nonleptonic decays and on Bs-Bsbar mixing. We conclude presenting an outlook on Lepton-Photon 2009.