840 research outputs found
A superweak solution of the Strong CP Problem
A non-axion solution to the Strong CP Problem is proposed that works even in
the context of gravity-mediated supersymmetry breaking. Both
and indirect CP violation in the are predicted
to be unobservably small. is predicted to arise,
typically, with branching ration . A new source of dark
matter is also predicted in the model.Comment: LaTex 12 page
Bimaximal Mixing in an SO(10) Minimal Higgs Model
An SO(10) SUSY GUT model was previously presented based on a minimal set of
Higgs fields. The quark and lepton mass matrices derived fitted the data
extremely well and led to large mixing of muon- and tau-neutrinos in agreement
with the atmospheric neutrino data and to the small-angle MSW solution for the
solar neutrinos. Here we show how a slight modification leading to a non-zero
up quark mass can result in bimaximal mixing for the atmospheric and solar
neutrinos. The "just-so" vacuum solution is slightly favored over the
large-angle MSW solution on the basis of the hierarchy required for the
right-handed Majorana matrix and the more nearly-maximal mixing angles
obtained.Comment: 10 pages, LaTeX, several references adde
How a Non-hierarchical Neutrino Mass Matrix Can Arise
One puzzle of neutrino masses and mixings is that they do not exhibit the
kind of strong "hierarchy" that is found for the quarks and charged leptons.
Neutrino mass ratios and mixing angles are not small. A possible reason for
this is proposed here. It is based on the fact that typical realistic grand
unified models contain particles with unification-scale masses which, when
integrated out, can yield a neutrino mass matrix that is not of the standard
seesaw form.Comment: 12 pages, 5 figures, LaTe
Explaining Why the u and d Quark Masses are Similar
An approach is suggested for modeling quark and lepton masses and mixing in
the context of grand unified theories that explains the curious fact that m_u ~
m_d even though m_t >> m_b. The structure of the quark mass matrices is such as
to allow a non-Peccei-Quinn solution of the Strong CP Problem.Comment: 11 pages, ReVTeX
Flavor Alignment Solutions to the Strong CP Problem in Supersymmetry
An approach to solving the Strong CP Problem in supersymmetric theories is
discussed which uses abelian family symmetries to align the mass matrices of
the quarks and squarks. In this way both the Strong CP Problem and the
characteristic flavor and CP problems of supersymmetry can be solved in a
single way.Comment: 13 pages, LaTe
Implications of a Minimal SO(10) Higgs Structure
A minimal SO(10) Higgs structure involving a single adjoint field along with
spinors, vectors and singlets has been shown to break the SO(10) gauge symmetry
to the standard model while stabilizing the F-flat directions and solving the
doublet-triplet splitting problem naturally. With this minimal set of Higgs
fields, we show how to construct quark and lepton mass matrices which explain
well the many features of the observed spectrum, including the Georgi-Jarlskog
mass relations. A large mixing of the muon- and tau-neutrinos results naturally
as observed in the atmospheric neutrino data. A particular model relying on a
family symmetry has been constructed which realizes the desired mass matrices.Comment: 10 pages, REVTEX, contribution submitted to NEUTRINO 98 Conferenc
Family Unification with SO(10)
Unification based on the group SO(10)^3 \times S_3 is studied. Each family
has its own SO(10) group, and the S_3 permutes the three families and SO(10)
factors. This is the maximal local symmetry for the known fermions. Family
unification is achieved in the sense that all known fermions are in a single
irreducible multiplet of the symmetry. The symmetry suppresses SUSY flavor
changing effects by making all squarks and sleptons degenerate in the symmetry
limit. Doublet-triplet splitting can arise simply, and non-trivial structure of
the quark and lepton masses emerges from the gauge symmetry, including the
"doubly lopsided" form.Comment: 11 pages, references adde
Family Symmetry, Gravity, and the Strong CP Problem
We show how in a class of models Peccei--Quinn symmetry can be realized as an
automatic consequence of a gauged family symmetry. These models provide
a solution to the strong CP problem either via a massless --quark or via the
DFSZ invisible axion. The local family symmetry protects against potentially
large corrections to induced by quantum gravitational
effects. In a supersymmetric extension, the `--problem' is shown to have a
natural solution in the context of gravitationally induced operators. We also
present a plausible mechanism which can explain the inter--generational mass
hierarchy in such a context.Comment: BA-92-79, 14 pages, in LaTeX, no figure
Visible Sector Supersymmetry Breaking Revisited
We revisit the possibility of "visible sector" SUSY models: models which are
straightforward renormalizable extensions of the Minimal Supersymmetric
Standard Model (MSSM), where SUSY is broken at tree level. Models of this type
were abandoned twenty years ago due to phenomenological problems, which we
review. We then demonstrate that it is possible to construct simple
phenomenologically viable visible sector SUSY models. Such models are indeed
very constrained, and have some inelegant features. They also have interesting
and distinctive phenomenology. Our models predict light gauginos and very heavy
squarks and sleptons. The squarks and sleptons may not be observable at the
LHC. The LSP is a stable very light gravitino with a significant Higgsino
admixture. The NLSP is mostly Bino. The Higgs boson is naturally heavy. Proton
decay is sufficently and naturally suppressed, even for a cutoff scale as low
as 10^8 GeV. The lightest particle of the O'Raifeartaigh sector (the LOP) is
stable, and is an interesting cold dark matter candidate.Comment: 23 pages, 3 figures, LaTe
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