Alex G. Dias

Naturally light right-handed neutrinos in a 3-3-1 Model

Abstract In this work we show that light right-handed neutrinos, with mass in the sub-eV scale, is a natural outcome in a 3–3–1 model. By considering effective dimension five operators, the model predicts three light right-handed neutrinos, weakly mixed with the left-handed ones. We show also that the model is able to explain the LSND experiment and still be in agreement with solar and atmospheric data for neutrino oscillation.

Concerning the Landau pole in 3-3-1 models

Abstract.Some 3-3-1 models predict the existence of a non-perturbative regime at the TeV scale. We study in these models and their supersymmetric extensions, the energy at which the non-perturbative limit and a Landau-like pole arise. An order of magnitude for the mass of the extra neutral vector boson,

Naturally light invisible axion in models with large local discrete symmetries

Z^\prime

Discrete symmetries, invisible axion, and lepton number symmetry in an economic 3-3-1 model

, present in these models is also obtained.

Stabilizing the invisible axion in 3-3-1 models

We show that by introducing appropriate local ZN(N>13) symmetries in electroweak models it is possible to implement an automatic Peccei-Quinn symmetry, at the same time keeping the axion protected against gravitational effects. Although we consider here only an extension of the standard model and a particular 3-3-1 model, the strategy can be used in any kind of electroweak model. An interesting feature of this 3-3-1 model is that if we add ~i! right-handed neutrinos, ~ii! the conservation of the total lepton number, and ~iii! a Z2 symmetry, the Z13 and the chiral Peccei-Quinn U(1)PQ symmetries are both accidental symmetries in the sense that they are not imposed on the Lagrangian but are just a consequence of the particle content of the model, its gauge invariance, renormalizability, and Lorentz invariance. In addition, this model has no domain wall problem.

Neutrino decay and neutrinoless double beta decay in a 3-3-1 model

We show that Peccei-Quinn and lepton number symmetries can be a natural outcome in a 3-3-1 model with right-handed neutrinos after imposing a Z11^ Z2 symmetry. This symmetry is suitably accommodated in this model when we augment its spectrum by including merely one singlet scalar field. We work out the breaking of the Peccei-Quinn symmetry, yielding the axion, and study the phenomenological consequences. The main result of this work is that the solution to the strong CP problem can be implemented in a natural way, implying an invisible axion phenomenologically unconstrained, free of domain wall formation, and constituting a good candidate for the cold dark matter. DOI: 10.1103/PhysRevD.68.115009

The little hierarchy in Universal Extra Dimensions

By introducing local

Naturally light invisible axion and local Z13⊗Z3 symmetries

Z_N

3–3–1 models at electroweak scale

symmetries with

Dynamical breakdown of symmetry in a (2+1)-dimensional model containing the Chern-Simons field

N=11,13