423 research outputs found
3-3-1 Models at Electroweak Scale
We show that in 3-3-1 models there exist a natural relation among the
coupling constant , the electroweak mixing angle , the
mass of the , and one of the vacuum expectation values, which implies that
those models can be realized at low energy scales and, in particular, even at
the electroweak scale. So that, being that symmetries realized in Nature, new
physics may be really just around the corner.Comment: 10 pages, version to be published in Physics Letters
Constraints on spin-3/2 and excited spin-1/2 fermions coming from the leptonic Z0-partial width
We consider effective interactions among excited spin-1/2 and spin-3/2
leptons with the usual ones. Assuming that these new leptons are lighter than
the Z0 we will study the constraints on their masses and compositeness scale
coming from the leptonic Z0 partial width.Comment: Typeset using REVTEX 2.0, 9 pages and 3 figures (available upon
request
Lepton masses in a supersymmetric 3-3-1 model
We consider the mass generation for both charginos and neutralinos in a 3-3-1
supersymmetric model. We show that R-parity breaking interactions leave the
electron and one of the neutrinos massless at the tree level. However the same
interactions induce masses for these particles at the 1-loop level. Unlike the
similar situation in the MSSM the masses of the neutralinos are related to the
masses of the charginos.Comment: RevTex, 11 pages incluing 2 .eps figures. Extended published versio
Infrared finite solutions for the gluon propagator and the QCD vacuum energy
Nonperturbative infrared finite solutions for the gluon polarization tensor
have been found, and the possibility that gluons may have a dynamically
generated mass is supported by recent Monte Carlo simulation on the lattice.
These solutions differ among themselves, due to different approximations
performed when solving the Schwinger-Dyson equations for the gluon polarization
tensor. Only approximations that minimize energy are meaningful, and, according
to this, we compute an effective potential for composite operators as a
function of these solutions in order to distinguish which one is selected by
the vacuum.Comment: 16 pages, latex file, 1 postscript figure, uses epsf.sty and
axodraw.sty. To be published in Phys. Lett.
The seesaw mechanism at TeV scale in the 3-3-1 model with right-handed neutrinos
We implement the seesaw mechanism in the 3-3-1 model with right-handed
neutrinos. This is accomplished by the introduction of a scalar sextet into the
model and the spontaneous violation of the lepton number. We identify the
Majoron as a singlet under symmetry, which makes it
safe under the current bounds imposed by electroweak data. The main result of
this work is that the seesaw mechanism works already at TeV scale with the
outcome that the right-handed neutrino masses lie in the electroweak scale, in
the range from MeV to tens of GeV. This window provides a great opportunity to
test their appearance at current detectors, though when we contrast our results
with some previous analysis concerning detection sensitivity at LHC, we
conclude that further work is needed in order to validate this search.Comment: about 13 pages, no figure
Neutrino masses through see-saw mechanism in 3-3-1 models
Some years ago it was shown by Ma that in the context of the electroweak
standard model there are, at the tree level, only three ways to generate small
neutrino masses by the see-saw mechanism via one effective dimension-five
operator. Here we extend this approach to 3-3-1 chiral models showing that in
this case there are several dimension-five operators and we also consider their
tree level realization.Comment: RevTex, 7 pages and 4 .eps figures. Version published in Phys. Rev.
D. with a change in the titl
Generating Neutrino Mass in the 331 Model
A mechanism for generating small tree-level Majorana mass for neutrinos is
implemented in the 331 Model. No additional fermions or scalars need to be
added, and no mass scale greater than a few TeV is invoked.Comment: LaTex, 7 pages, no figures. Revised version to appear in Phys. Rev.
Seesaw tau lepton mass and calculable neutrino masses in a 3-3-1 model
In a version of the 3-3-1 model proposed by Duong and Ma the introduction of
the scalar sextet for giving mass to the charged leptons is avoided by adding a
singlet charged lepton. We show that in this case the lepton gains mass
through a seesaw--like mechanism. Besides we show how to generate neutrino
masses at the tree and at the 1-loop level with the respective
Maki-Nakagawa-Sakata leptonic mixing matrices.Comment: revtex, 5 pages and one eps figure. Published versio
Bounds on the electromagnetic interactions of excited spin-3/2 leptons
We discuss possible deviations from QED produced by a virtual excited
spin-3/2 lepton in the reaction . Data recorded
by the OPAL Collaboration at a c.m. energy are used to
establish bounds on the nonstandard-lepton mass and coupling strengths.Comment: Latex, 5 pages, 7 ps figures. To be published in Phys. Rev.
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