Study of CP violation in SU(2)/sub L/ x SU(2)/sub R/ x U(1) electroweak models

It has been shown recently that the ratio of CP violating phases in a minimal SU(2)/sub L/ x SU(2)/sub R/ x U(1) electroweak model with spontaneous CP violation and a discrete left-right symmetry can be calculated in terms of quark masses and (for two generations) the Cabibbo angle, provided that the ratio of the parameters kappa and kappa' involved in the Higgs Vacuum expectation value can be treated as a perturbation parameter. They have carried out such a calculation in a more general model, obtained from the above model by removing the requirement of invariance under the discrete left-right transformation and have shown that the resulting CP violating phases depend apart from previous parameters on (for two generations) only one additional parameter: the right-handed quark mixing angle Theta/sub R/. They have studied some of the phenomenological implications of the model and determined the allowed values of the parameter absolute value epsilon'/sub LR/epsilon/sub LR/. It has recently been shown that in symmetric SU(2)/sub L/ x SU(2)/sub R/ x U(1) models, the minimal number of Higgs fields required to break the gauge symmetry to U(1)/sub em/ (and generate fermion masses) are insufficient to allow for the presence of spontaneous CP violation. They have studied this issue in detail and shown that the same is also true for non-symmetric models