313 research outputs found
Neutrino mixing from the double tetrahedral group T^{\prime}
It is shown that it is possible to create successful models of flavor for
both quarks and leptons using the discrete non-abelian group by
itself. Two simple realizations are presented that can be used as the starting
point for more general scenarios. In addition to the Minimal Supersymmetric
Standard Model particle content, the models include three generations of right
handed neutrinos and four scalar flavon fields. Three of the flavons are needed
in the quark and charged lepton sector of the models and the fourth flavon
participates only in the neutrino sector.Comment: 4 pages, no figures. References added and minor typos corrected.
Version to appear in PR
Models of Flavor with Discrete Symmetries
In an attempt to understand the observed patterns of lepton and quark masses,
models invoking a flavor symmetry , under which the Standard Model
generations are charged, have been proposed. One particularly successful
symmetry, U(2), has been extensively discussed in the literature. The Yukawa
matrices in models based on this symmetry reproduce the observed mass ratios in
the lepton and quark sectors. The features of the symmetry that determine the
texture of the Yukawa matrices can be found in other symmetries as well. We
present a model based on a minimal, non-Abelian discrete symmetry that
reproduces the Yukawa matrices associated with U(2) theories of flavor. In
addition to reproducing the mass and mixing angle relations obtained in such
theories, the different representation structure of our new horizontal symmetry
allows for solutions to the solar and atmospheric neutrino problems.Comment: Prepared for the 8th Mexican Workshop on Particles and Fields,
Zacatecas, Mexico; 14-20 November, 200
Standard Model Extension with Flipped Generations
An extension of the Standard Model is presented that leads to the possible
existence of new gauge bosons with masses in the range of a few TeV. Due to the
fact that their couplings to Standard Model fermions are strongly suppressed,
it is possible for them to be hidden from current searches. The model contains
additional generations of fermions with quantum numbers resembling those of the
Standard Model fermion generations but with a twist: their charge assignments
are such that their electric charges and chiralities are flipped with respect
to those of their corresponding Standard Model counterparts. This feature
provides a way to obtain potential dark matter candidates and the interesting
possibility for a Lepton number conserving dimension-five operator for Dirac
neutrino masses. The model implications associated to electroweak precision
parameters, flavor changing neutral currents, and diphoton rate contributions
are briefly discussed. The general assumptions of this set up are also used to
sketch a couple of variants of the model with peculiar features that could
motivate further study.Comment: 8 pages, 3 figures, 2 tables. Discussion on W' boson and RH neutrinos
extended, references added, typos corrected, title changed. Matches published
version in PL
A new radiative neutrino mass generation mechanism with higher dimensional scalar representations and custodial symmetry
A new realization for radiative neutrino mass generation is presented. Based
on the requirement of tree-level custodial symmetry and the introduction of
higher (greater than two) dimensional representations for scalar fields, a
specific scenario with a scalar septet is presented that generates neutrino
Majorana masses radiatively. This is accomplished through an eleven dimensional
operator that requires the addition of several scalar fields and a SU(2) 5-plet
of new fermions, together with a Z2 that guarantees the preservation of
custodial symmetry. The phenomenology of the setup is rather rich and includes
a dark matter candidateComment: 4 pages, 1 figure, references added, matches version to appear in
Physics Letters
Bosonic Topcolor
A topcolor model is presented that contains both composite and fundamental
scalar fields. Strong dynamics accounts for most of the top quark mass and part
of the electroweak symmetry breaking scale. The fundamental scalar is weakly
coupled and transmits its share of electroweak symmetry breaking to the light
fermions. The model is allowed by the current experimental bounds, and can give
a potentially large contribution to mixing.Comment: Talk given by A. Aranda at DPF 2000, Ohio State, August 200
Gauge-Higgs unification with brane kinetic terms
By identifying the Higgs field as an internal component of a higher
dimensional gauge field it is possible to solve the little hierarchy problem.
The construction of a realistic model that incorporates such a gauge-Higgs
unification is an important problem that demands attention. In fact, several
attempts in this direction have already been put forward. In this letter we
single out one such attempt, a 6D SU(3) extended electroweak theory, where it
is possible to obtain a Higgs mass prediction in accord with global fits. One
shortcoming of the model is its prediction for the Weinberg angle, it is too
large. We slightly modify the model by including brane kinetic terms in a way
motivated by the orbifold action on the 6D fields. We show that in this way it
is possible to obtain the correct Weinberg angle while keeping the desired
results in the Higgs sector.Comment: 11 pages, 2 figures. References added. Version to appear in Phys.
Lett.
CP violating phase from charged-lepton mixing
A model independent analysis of the leptonic Dirac CP-violating phase
({\delta}) is presented. The analysis uses the experimentally determined values
of the mixing angles in the lepton mixing matrix in order to explore the
allowed values for {\delta} and possible general forms for the charged lepton
mixing matrix. This is done under two general assumptions: 1) that the mixing
matrix in the neutrino sector is the so-called tribimaximal matrix and hence
the non zero value for {\theta}13 arises due to the mixing matrix in the
charged lepton sector and 2) the charged lepton mixing matrix is parametrized
in terms of three angles and one phase. It is found that any value of {\delta}
is still consistent with the data and that, considering the assumptions above,
regardless of the value for {\delta}, the 1-3 mixing angle in the charged
lepton sector is small but non zero and the 2-3 mixing angle can take values in
only two possible small ranges around 0 and {\pi}/2 respectively.Comment: References adde
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