New physics in CP violation experiments

CP violation plays a privileged role in our quest for new physics beyond the electroweak standard model. In the standard model, the violation of CP in the weak interactions has a single source: the phase of the quark mixing matrix (the CKM matrix, for Cabibbo-Kobayashi-Maskawa). Most extensions of the standard model exhibit new sources of CP violation. For instance, the truly minimal supersymmetric extension of the standard model has two new phases in addition to the CKM phase. Given that CP violation is so tiny in the kaon system, is still largely unexplored in B physics, and is negligibly small in the electric dipole moments, it is clear that new physics may have a good chance to manifest some departure from the standard model in this particularly challenging class of rare phenomena. On the other hand, it is also apparent that CP violation generally represents a major constraint on any attempt at model building beyond the standard model, In this review, we tackle these two sides of the relation between CP violation and new physics. Our focus will be on the potentialities to use CP violation as a probe on supersymmetric (SUSY) extensions of the standard model. We wish to clarify the extent to which such indirect signals for SUSY are linked to a fundamental theoretical issue: Is there a relation between the mechanism that originates the whole flavor structure and the mechanism that is responsible for the breaking of supersymmetry? Different ways to answer this question lead to quite different expectations for CP violation in B physics.