Narrow Results

The unjustly neglected method of exactly solving generalized electroweak models — with an original spontaneous symmetry breaking mechanism based on the gauge group SU(n)_L⊗U(1)_Y — is applied here to a particular class of chiral 3-3-1 models. This procedure enables us, without resorting to any approximation, to express the boson mass spectrum and charges of the particles involved therein as a straightforward consequence of both a proper parametrization of the Higgs sector and a new generalized Weinberg transformation. We prove that the resulting values can accommodate the experimental ones just by tuning a sole parameter. Furthermore, if we take into consideration both the left-handed and right-handed components of the neutrino (included in a lepton triplet along with their corresponding left-handed charged partner), then we are in the position to propose an original method for the neutrino to acquire a very small but nonzero mass without spoiling the previously achieved results in the exact solution of the model. In order to be compatible with the existing phenomenological data, the range of that sole parameter imposes a large order of magnitude for the vev〈ϕ〉~10⁴ TeV in our method. Consequently, the new bosons of the model have to be very massive.

By making a renormalization group analysis we explore the possibility of having a 331 model as the only intermediate gauge group between the standard model and the scale of unification of the three coupling constants. We shall assume that necessarily there is no group of grand unification at the scale of convergence of the couplings. With this scenario, different 331 models and their corresponding supersymmetric versions are considered, and we find the versions that allow the symmetry breaking described above. Besides, the allowed interval for the 331 symmetry breaking scale, and the behavior of the running coupling constants are obtained. It is worth saying that some of the supersymmetric scenarios could be natural frameworks for split supersymmetry. Finally, we look for possible 331 models with a simple group at the grand unification scale that could fit the symmetry breaking scheme described above.

Processes τ→lγ, τ→lll with l = e, μ and μ(τ) →e (μ) γ are evaluated in the framework of a model based on the extended symmetry gauge SU(3)_c ⊗SU(3)_L ⊗U(1)_Y with a leptonic sector consisting of five triplets. Lepton flavor violating processes are allowed at tree level in this model through the new Z′ gauge boson. We obtained bounds for the mixing angles in the leptonic sector of the model, considering the experimental measurements of the processes from the BELLE and the BABAR collaborations.