70 research outputs found
Dicyclic Horizontal Symmetry and Supersymmetric Grand Unification
It is shown how to use as horizontal symmetry the dicyclic group in a supersymmetric unification where
one acts on the first and second families, in a horizontal doublet, and
the other acts on the third. This can lead to acceptable quark masses and
mixings, with an economic choice of matter supermultiplets, and charged lepton
masses can be accommodated.Comment: 10 pages, LaTe
Bilinear R-parity violation with flavor symmetry
Bilinear R-parity violation (BRPV) provides the simplest intrinsically
supersymmetric neutrino mass generation scheme. While neutrino mixing
parameters can be probed in high energy accelerators, they are unfortunately
not predicted by the theory. Here we propose a model based on the discrete
flavor symmetry with a single R-parity violating parameter, leading to
(i) correct Cabbibo mixing given by the Gatto-Sartori-Tonin formula, and a
successful unification-like b-tau mass relation, and (ii) a correlation between
the lepton mixing angles and in agreement with
recent neutrino oscillation data, as well as a (nearly) massless neutrino,
leading to absence of neutrinoless double beta decay.Comment: 16 pages, 3 figures. Extended version, as published in JHE
Fermion Electric Dipole Moments in Supersymmetric Models with R-parity Violation
We analyze the electron and neutron electric dipole moments induced by
R-parity violating interactions in supersymmetric models. It is pointed out
that dominant contributions can come from one-loop diagrams involving both the
bilinear and trilinear R-parity odd couplings, leading to somewhat severe
constraints on the products of those couplings.Comment: Revtex, 19pp, four figures in axodraw.st
A Supersymmetric Theory of Flavor and R Parity
We construct a renormalizable, supersymmetric theory of flavor and parity
based on the discrete flavor group . The model can account for all the
masses and mixing angles of the Standard Model, while maintaining sufficient
squark degeneracy to circumvent the supersymmetric flavor problem. By starting
with a simpler set of flavor symmetry breaking fields than we have suggested
previously, we construct an economical Froggatt-Nielsen sector that generates
the desired elements of the fermion Yukawa matrices. With the particle content
above the flavor scale completely specified, we show that all renormalizable
-parity-violating interactions involving the ordinary matter fields are
forbidden by the flavor symmetry. Thus, parity arises as an accidental
symmetry in our model. Planck-suppressed operators that violate parity, if
present, can be rendered harmless by taking the flavor scale to be GeV.Comment: 28 pp. LaTeX, 1 Postscript Figur
Supersymmetric Froggatt-Nielsen Models with Baryon- and Lepton-Number Violation
We systematically investigate the embedding of U(1)_X Froggatt-Nielsen models
in (four-dimensional) local supersymmetry. We restrict ourselves to models with
a single flavon field. We do not impose a discrete symmetry by hand, e.g.
R-parity, baryon-parity or lepton-parity. Thus we determine the order of
magnitude of the baryon- and/or lepton violating coupling constants through the
Froggatt-Nielsen mechanism. We then scrutinize whether the predicted coupling
constants are in accord with weak or GUT scale constraints. Many models turn
out to be incompatible.Comment: Final version, references added, minor corrections; LaTeX, 46 page
REALISTIC MODELS WITH A LIGHT U(1) GAUGE BOSON COUPLED TO BARYON NUMBER
We recently showed that a new gauge boson coupling only to baryon
number is phenomenologically allowed, even if and . In our previous work we assumed that kinetic mixing between the baryon
number and hypercharge gauge bosons (via an term)
was small enough to evade constraints from precision electroweak measurements.
In this paper we propose a class of models in which this term is naturally
absent above the electroweak scale. We show that the generation of a mixing
term through radiative corrections in the low-energy effective theory does not
lead to conflict with precision electroweak measurements and may provide a
leptonic signal for models of this type at an upgraded Tevatron.Comment: 21 pages, LaTeX, 4 figures in a uuencoded compressed postscript file
Neutrino Masses and Mixing in Supersymmetric Models without Parity
We study neutrino masses and mixing in Supersymmetric Models without
parity and with generic soft Supersymmetry breaking terms. Neutrinos acquire
mass from various sources: tree level neutrino--neutralino mixing, loop effects
and non--renormalizable operators. Abelian horizontal symmetries (invoked to
explain the smallness and hierarchy in quark parameters) replace parity in
suppressing neutrino masses. We find lower bounds on the mixing angles:
\sin\theta_{ij} \gsim m(\ell_i^-)/m(\ell_j^-) () and unusual order of
magnitude predictions for neutrino mass ratios:
; (). Bounds from laboratory experiments exclude
m_{\nu_\tau} \gsim 3\ MeV and the cosmological constraint that excludes
m_{\nu_\tau} \gsim 100\ eV is not evaded. Neither the solar nor the
atmospheric neutrino problems are likely to be solved by
oscillations. These conclusions can be evaded if holomorphy plays an important
role in the lepton Yukawa couplings.Comment: 16 pages, harvmac, no figures; Version to appear in Phys. Lett.
Predictions from an Anomalous U(1) Model of Yukawa Hierarchies
We present a supersymmetric standard model with three gauged Abelian
symmetries, of a type commonly found in superstrings. One is anomalous, the
other two are family symmetries. It has a vacuum in which only these
symmetries are broken by stringy effects. It reproduces all observed quark and
charged lepton Yukawa hierarchies, and the value of the Weinberg angle. It
predicts three massive neutrinos, with mixing that can explain both the small
angle MSW effect, and the atmospheric neutrino anomaly. The Cabibbo angle is
expressed in terms of the gauge couplings at unification. It conserves
R-parity, and proton decay is close to experimental bounds.Comment: 26 page
Supersymmetry without R-Parity and without Lepton Number
We investigate Supersymmetric models where neither R parity nor lepton number
is imposed. Neutrino masses can be kept highly suppressed compared to the
electroweak scale if the -terms in the superpotential are aligned with the
SUSY-breaking bilinear -terms. This situation arises naturally in the
framework of horizontal symmetries. The same symmetries suppress the trilinear
R parity violating terms in the superpotential to an acceptable level.Comment: 18 pages, harvma
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