WeinbergCP-violation model revisited

Abstract

Chiral properties of the weak amplitudes in the Weinberg model of CP violation are carefully treated. The CP-odd K→2π amplitude is chiral-symmetry nonlinear-realization dependent, and so is the soft-pion relation. This realization dependence is canceled by the pole contribution arising from the combination of a strong Kπ vertex and a K-vacuum tadpole, so that to lowest order in chiral symmetry the physical K→2π amplitude is chiral-model independent. The vacuum-insertion method is valid only in a particular realization scheme. Various CP-violating effects are then reexamined in this model. When the η-η’ mixing is taken into account, ε’/ε≊-0.007 is obtained. The electric dipole moment of a neutron due to neutral-Higgs-boson exchange and the current experimental limit are used to set an upper bound for neutral-Higgs-boson mixing. Finally, CP violation in K→3π decays is discussed.