2,557 research outputs found
Explicit SO(10) Supersymmetric Grand Unified Model for the Higgs and Yukawa Sectors
A complete set of fermion and Higgs superfields is introduced with
well-defined SO(10) properties and U(1) x Z_2 x Z_2 family charges from which
the Higgs and Yukawa superpotentials are constructed. The structures derived
for the four Dirac fermion and right-handed Majorana neutrino mass matrices
coincide with those previously obtained from an effective operator approach.
Ten mass matrix input parameters accurately yield the twenty masses and mixings
of the quarks and leptons with the bimaximal atmospheric and solar neutrino
vacuum solutions favored in this simplest version.Comment: Published version appearing in PRL in which small modifications to
original submission and a paragraph concerning proton decay appea
Realization of the Large Mixing Angle Solar Neutrino Solution in an SO(10) Supersymmetric Grand Unified Model
An SO(10) supersymmetric grand unified model proposed earlier leading to the
solar solution involving ``just-so'' vacuum oscillations is reexamined to study
its ability to obtain the other possible solar solutions. It is found that all
four viable solar neutrino oscillation solutions can be achieved in the model
simply by modification of the right-handed Majorana neutrino mass matrix, M_R.
Whereas the small mixing and vacuum solutions are easily obtained with several
texture zeros in M_R, the currently-favored large mixing angle solution
requires a nearly geometric hierarchical form for M_R that leads by the seesaw
formula to a light neutrino mass matrix which has two or three texture zeros.
The form of the matrix which provides the ``fine-tuning'' necessary to achieve
the large mixing angle solution can be understood in terms of Froggatt-Nielsen
diagrams for the Dirac and right-handed Majorana neutrino mass matrices. The
solution fulfils several leptogenesis requirements which in turn can be
responsible for the baryon asymmetry in the universe.Comment: 14 pages including 2 figure
Continuations of the nonlinear Schr\"odinger equation beyond the singularity
We present four continuations of the critical nonlinear \schro equation (NLS)
beyond the singularity: 1) a sub-threshold power continuation, 2) a
shrinking-hole continuation for ring-type solutions, 3) a vanishing
nonlinear-damping continuation, and 4) a complex Ginzburg-Landau (CGL)
continuation. Using asymptotic analysis, we explicitly calculate the limiting
solutions beyond the singularity. These calculations show that for generic
initial data that leads to a loglog collapse, the sub-threshold power limit is
a Bourgain-Wang solution, both before and after the singularity, and the
vanishing nonlinear-damping and CGL limits are a loglog solution before the
singularity, and have an infinite-velocity{\rev{expanding core}} after the
singularity. Our results suggest that all NLS continuations share the universal
feature that after the singularity time , the phase of the singular core
is only determined up to multiplication by . As a result,
interactions between post-collapse beams (filaments) become chaotic. We also
show that when the continuation model leads to a point singularity and
preserves the NLS invariance under the transformation and
, the singular core of the weak solution is symmetric
with respect to . Therefore, the sub-threshold power and
the{\rev{shrinking}}-hole continuations are symmetric with respect to ,
but continuations which are based on perturbations of the NLS equation are
generically asymmetric
Texture of fermion mass matrices in partially unified theories
We investigate the texture of fermion mass matrices in theories with partial
unification (for example ) at a scale
GeV. Starting with the low energy values of the masses and the
mixing angles, we find only two viable textures with atmost four texture zeros.
One of these corresponds to a somewhat modified Fritzsch textures. A
theoretical derivataion of these textures leads to new interesting relations
among the masses and the mixing angles.Comment: 10 pages(Latex
Unique Mass Texture for Quarks and Leptons
Texture specific quark mass matrices which are hermitian and hierarchical are
examined in detail . In the case of texture 6 zeros matrices, out of sixteen
possibilities examined by us, none is able to fit the low energy data (LED),
for example, , ,
, lies in the range (PDG). Similarly none of the 32 texture 5 zeros mass matrices considered
is able to reproduce LED. In particular, the latest data from LEP regarding
rules out all of them. In the texture 4
zeros case, we find that there is a unique texture structure for and
mass matrices which is able to fit the data.Comment: 12 pages, LaTeX,some changes in the references,minor changes in the
text,to appear in Phys Rev D(Rapid communications
Non-Universal Correction To And Flavor Changing Neutral Current Couplings
A non-universal interaction associated with top quark induces flavor changing
neutral currents (FCNC) among light fermions. The size of the FCNC effect
depends crucially on the dynamics of the fermion mass generation. In this
paper, we study the effect of a non-universal interaction on ,
{\it etc}, by using an effective lagrangian technique and assuming the quark
mass matrices in the form of a generalized Fritzsch ansatz. We point out that
if fitting to the LEP data within , the induced FCNC couplings
are very close to the experimental limits.Comment: 9 pages, Te
Symmetric Textures in SO(10) and LMA Solution for Solar Neutrinos
We analyze a model based on SUSY SO(10) combined with SU(2) family symmetry
and symmetric mass matrices constructed by the authors recently. Previously,
only the parameter space for the LOW and vacuum oscillation (VO) solutions was
investigated. We indicate in this note the parameter space which leads to large
mixing angle (LMA) solution to the solar neutrino problem with a slightly
modified effective neutrino mass matrix. The symmetric mass textures arising
from the left-right symmetry breaking and the SU(2) symmetry breaking give rise
to very good predictions for the quark and lepton masses and mixing angles. The
prediction of our model for the |U_{e\nu_{3}}| element in the
Maki-Nakagawa-Sakata (MNS) matrix is close to the sensitivity of current
experiments; thus the validity of our model can be tested in the near future.
We also investigate the correlation between the |U_{e\nu_{3}}| element and
\tan^{2}\theta_{\odot} in a general two-zero neutrino mass texture.Comment: RevTeX4; 9 pages; 1 figur
Lepton Flavour Violation in a Class of Lopsided SO(10) Models
A class of predictive SO(10) grand unified theories with highly asymmetric
mass matrices, known as lopsided textures, has been developed to accommodate
the observed mixing in the neutrino sector. The model class effectively
determines the rate for charged lepton flavour violation, and in particular the
branching ratio for , assuming that the supersymmetric GUT
breaks directly to the constrained minimal supersymmetric standard model
(CMSSM). We find that in light of the combined constraints on the CMSSM
parameters from direct searches and from the WMAP satellite observations, the
resulting predicted rate for in this model class can be
within the current experimental bounds for low , but that the next
generation of experiments would effectively rule out this
model class if LFV is not detected.Comment: 23 page
Large Angle MSW Solution in Grand Unified Theories with SU(3) X U(1) Horizontal Symmetry
We construct a model with a SU(3) X U(1) horizontal symmetry in the context
of Grand Unified Theories. In our models, the bi-maximal lepton mixing and
suitable neutrino masses for the large angle MSW solution are obtained without
any fine-tuning due to the spontaneously broken SU(3)_H symmetry. The three
generations of quarks and leptons are unified as members of the SU(3)_H
fundamental representation, and the U(1)_H charge gives the origin of the
fermion mass hierarchy and mixing angles. We present two explicit examples of
SU(5)_GUT and SO(10)_GUT models, in which the Yukawa structures are given
successfully.Comment: 23 pages, 6 figures, references adde
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