In the context of the standard model the quantization of the electric charge occurs only family by family. When we consider the three families together with massless neutrinos the electric charge is not quantized any more. Here we show that a chiral bilepton gauge model based on the gauge group SU(3) C SU(3) L U(1) N explains the quantization of the electric charge when we take into account the three families of fermions. This result does not depend on the neutrino masses. Charge quantization occurs whether the neutrinos are massless or Dirac or Majorana massive fields. ͓S0556-2821͑98͒02115-8͔ PACS number͑s͒: 12.60. Cn, 12.90.ϩb

We show that it is possible to implement soft superweak CP violation in the context of a 3-3-1 model with only three triplets. All CP violation effects come from the exchange of singly and doubly charged scalars. We consider the implication of this mechanism in the quark and lepton sectors. In particular it is shown that, in this model, as in most of those which incorporate scalar mediated CP violation, it is possible to have large electric dipole moments for the muon and the tau lepton while keeping small those of the electron and neutron. The CKM mixing matrix is real at the tree level but gets a phase at the 1-up loop level. ͓S0556-2821͑99͒04117-X͔

We consider a model with soft CP violation which accommodates the CP violation in the neutral kaons even if we assume that the Cabibbo-Kobayashi-Maskawa mixing matrix is real and the sources of CP violation are three complex vacuum expectation values and a trilinear coupling in the scalar potential. We show that for some reasonable values of the masses and other parameters the model allows us to explain all the observed CP violation processes in the K 0 -K 0 system.

We propose a left-right symmetric model, with the scalar sector consisting of two doublets and several bidoublets, in which neutrinos remain as Dirac fermions in all orders in perturbation theory. Although with only two bidoublets the neutrino masses still need a ne-tuning, this is not the case when a third bidoublet is added. One of the scalar doublets may be inert, since the left-right symmetry forbids it to couple with fermions.

We consider the implementation of CP violation in the context of 331 models. In particular we treat a model where only three scalar triplets are needed in order to give all fermions a mass while keeping neutrino massless. In this case all CP violation is provided by the scalar sector.