arXiv subjects
Publications and source records attributed to V. Pleitez.
Here we analyze the relation between the search for muonium to antimuonium conversion and the 331 model with doubly charged bileptons. We show that the constraint on the mass of the vector bilepton obtained by experimental data can be evaded even in the minimal version of the model since there are other contributions to that conversion. We also discuss the condition for which the experimental data constraint is valid.
Flavor changing (FC) neutrino-matter interactions can account for the zenith-angle dependent deficit of atmospheric neutrinos observed in the SuperKamiokande experiment, without directly invoking neither neutrino mass, nor mixing. We find that FC $ν_μ$-matter interactions provide a good fit to the observed zenith angle distributions, comparable in quality to the neutrino oscillation hypothesis. The required FC interactions arise naturally in many attractive extensions of the Standard Model.
Several left-right parity violating asymmetries in lepton-lepton scattering in fixed target and collider experiments are considered as signals for doubly charged vector bosons (bileptons).
In a 331 model in which the lepton masses arise from a scalar sextet it is possible to break spontaneously a global symmetry implying in a pseudoscalar majoron-like Goldstone boson. This majoron does not mix with any other scalar fields and for this reason it does not couple, at the tree level, neither to the charged leptons nor to the quarks. Moreover, its interaction with neutrinos is diagonal. We also argue that there is a set of the parameters in which that the model can be consistent with the invisible Z^0-width and that heavy neutrinos can decay sufficiently rapid by majoron emission having a lifetime shorter than the age of the universe.
We point out that if the majoron-like scheme is implemented within a 331 model, there must exist at least three different mass scales for the scalar vacuum expectation values in the model.
We show that the Higgs resonance can be amplified in a 3-3-1 model with a multi-Higgs "leptophilic" scalar sector. This would allow the observation of the Higgs particle in muon colliders even for Higgs masses considerably higher than the ones expected to be seen in the electroweak standard model framework.
We show that it is possible to implement soft superweak CP violation in the context of a 331 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 the 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 the neutron. The CKM mixing matrix is real up to the two loop level.
We argue in favor of the existence of the LIPs, the least interacting particles, which would only interact with ordinary matter through gravitational field and could account for (at least) part of the dark matter. The detectability of LIP matter is addressed at the end.
Although we accept that Physics is, as a last resort, an experimental science, the relationship between theory and experiment is far away from being trivial. Any experiment is always explained within a determinate theoretical context and, at the same time, an experiment can give suggestions for theories or even can bring new theoretical challenges. Thus, we cannot say without ambiguity when an experiment is a crucial one.
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.
We consider, in the electroweak standard model context, several left-right asymmetries in $μe$ elastic scattering at fixed target and collider experiments. For the former case, we show that the muon mass effects are important in a wide energy range. We also show that these asymmetries are sensitive to the electroweak mixing angle $θ_W$. The effect of an extra $Z'$ neutral vector boson appearing in a 331 model is also considered. The capabilities of these asymmetries in the search of this extra $Z'$ are addressed.
Several parity violating left-right asymmetries in Møller electron-electron and muon-muon scattering are considered in the context of the electroweak standard model at tree level in fixed target and collider experiences. We show that in colliders the asymmetry with only one of the beam polarized is large enough to compensate the smaller cross section at high energies. We also show that these asymmetries are very sensitive to a doubly charged vector bilepton resonance but they are insensitive to scalar ones.
Two models with $SU(3)_C\otimes SU(3)_L\otimes U(1)_N$ gauge symmetry are considered. We show that the masslessness of the photon does not prevent the neutrinos from acquiring Majorana masses. That is, there is no relation between the VEVs of Higgs fields and the electromagnetic gauge invariance contrary to what has been claimed recently.
We point out that the usual experimental upper bounds on the ``tau-neutrino mass'' do not apply if neutrino mixing is considered. The suppression of the population of the tau decay spectrum near the end-point, caused by mixing, may be compensated by an enhancement due to a resonant mechanism of hadronization. It is necessary therefore to analyse the whole spectrum to infer some limit to the ``tau-neutrino mass". We argue that, consequently, neutrino mixing evades the objection to interpret KARMEN anomaly as a heavy sequential neutrino.
We find an exact analytic solution for the time evolution of a three Dirac neutrino system adiabatically oscillating in matter, constructing explicitly the relevant $3\times 3$ mixing matrix in matter. Using this result we investigate the solar neutrino data in a scenario where the neutrino masses are such that $m_1\alt m_2\ll m_3$, taking into account several phenomenological constraints on neutrino mixing angles and masses. A solution of the solar neutrino problem for large values of the parameter $δm^2=m_2^2-m_1^2$ which are not usually associated with a resonance is found. This is an essentially three-generation effect.
We study two 3-3-1 models with i) five (four) charge 2/3 ($-1/3$) quarks and, ii) four (five) charge 2/3 ($-1/3$) quarks and a vector-like third generation. Possibilities beyond these models are also briefly considered.
We investigate the solar neutrino problem in the scenario of three generation neutrino oscillation hypothesis, taking into account other phenomenological constraints to the neutrino mixing and mass parameters.
We consider, in the context of a 331 model with a single neutral right-handed singlet, the generation of lepton masses. At zeroth order two neutrinos and one charged lepton are massless, while the other leptons, two neutrinos and two charged leptons, are massive. However the charged ones are still mass degenerate. The massless fields get a mass through radiative corrections which also break the degeneracy in the charged leptons.