Supersymmetry and a rationale for small CP violating phases

Abstract

We analyse the CP problem in the context of a supersymmetric extension of the standard model with universal strength of Yukawa couplings. A salient feature of these models is that the CP phases are constrained to be very small by the hierarchy of the quark masses, and the pattern of CKM mixing angles. This leads to a small amount of CP violation from the usual KM mechanism and a significant contribution from supersymmetry is required. Due to the large generation mixing in some of the supersymmetric interactions, the electric dipole moments impose severe constraints on the parameter space, forcing the trilinear couplings to be factorizable in matrix form. We find that the LL mass insertions give the dominant gluino contribution to saturate epsilon_K. The chargino contributions to epsilon'/epsilon are significant and can accommodate the experimental results. In this framework, the standard model gives a negligible contribution to the CP asymmetry in B-meson decay, a_{J/\psi K_s}. However, due to supersymmetric contributions to B_d-\bar{B}_d mixing, the recent large value of a_{J/\psi K_s} can be accommodated.