714 research outputs found
Symmetryless Dark Matter
It is appealing to stabilize dark matter by the same discrete symmetry that
is used to explain the structure of quark and lepton mass matrices. However, to
generate the observed fermion mixing patterns, any flavor symmetry must
necessarily be broken, rendering dark matter unstable. We study singlet,
doublet and triplet SU(2) multiplets of both scalar and fermion dark matter
candidates and enumerate the conditions under which no d < 6 dark matter decay
operators are generated even in the case if the flavor symmetry is broken to
nothing. We show that the VEVs of flavon scalars transforming as higher
multiplets (e.g. triplets) of the flavor group must be at the electroweak
scale. The most economical way for that is to use SM Higgs boson(s) as flavons.
Such models can be tested by the LHC experiments. This scenario requires the
existence of additional Froggatt-Nielsen scalars that generate hierarchies in
Yukawa couplings. We study the conditions under which large and small flavor
breaking parameters can coexist without destabilizing the dark matter.Comment: 8 pages, no figure
The golden ratio prediction for the solar neutrino mixing
We present a simple texture that predicts the cotangent of the solar neutrino
mixing angle to be equal to the golden ratio. This prediction is 1.4 standard
deviations below the present best-fit value and final SNO and KamLAND data
could discriminate it from tri-bi-maximal mixing. The neutrino mass matrix is
invariant under a Z_2 x Z'_2 symmetry: that geometrically is a reflection along
the diagonal of the golden rectangle. Assuming an analogous structure in the
quark sector suggests a golden prediction for the Cabibbo angle, theta_C =
pi/4- theta_12 = 13.3 degree, up to uncertainties comparable to V_{ub}.Comment: 5 pages. Final version, to appear on PR
Gauged Discrete Symmetries and Proton Stability
We discuss the results of a search for anomaly free Abelian Z_N discrete
symmetries that lead to automatic R-parity conservation and prevents dangerous
higher-dimensional proton decay operators in simple extensions of the minimal
supersymmetric extension of the standard model (MSSM) based on the left-right
symmetric group, the Pati-Salam group and SO(10). We require that the
superpotential for the models have enough structures to be able to give correct
symmetry breaking to MSSM and potentially realistic fermion masses. We find
viable models in each of the extensions and for all the cases, anomaly freedom
of the discrete symmetry restricts the number of generations.Comment: 8 pages, 2 figures; v2 : typos fixed, references adde
R-Parity Violation and Non-Abelian Discrete Family Symmetry
We investigate the implications of R-parity violating operators in a model
with family symmetry. The family symmetry can determine the form of R-parity
violating operators as well as the Yukawa matrices responsible for fermion
masses and mixings. In this paper we consider a concrete model with non-abelian
discrete symmetry Q_6 which contains only three R-parity violating operators.
We find that ratios of decay rates of the lepton flavor violating processes are
fixed thanks to the family symmetry, predicting BR(tau to 3e)/BR(tau to 3mu) ~
4 m_{mu}^2/m_{tau}^2.Comment: 20 pages, 3 figure
Label-free imaging by stimulated parametric emission microscopy reveals a difference in hemoglobin distribution between live and fixed erythrocytes
Hieu M. Dang, Gen Omura, Toshiyuki Omano, Masatomo Yamagiwa, Shin'ichiro Kajiyama, Yasuyuki Ozeki, Kazuyoshi Itoh, and Kiichi Fukui "Label-free imaging by stimulated parametric emission microscopy reveals a difference in hemoglobin distribution between live and fixed erythrocytes," Journal of Biomedical Optics 14(4), 040506 (1 July 2009). https://doi.org/10.1117/1.320715
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
Non-Abelian Discrete Flavor Symmetries on Orbifolds
We study non-Abelian flavor symmetries on orbifolds, and .
Our extra dimensional models realize , , and
including and . In addition, one can also realize
their subgroups such as , , etc. The flavor symmetry can be
realized on both and orbifolds.Comment: 16 page
Accidental stability of dark matter
We propose that dark matter is stable as a consequence of an accidental Z2
that results from a flavour-symmetry group which is the double-cover group of
the symmetry group of one of the regular geometric solids. Although
model-dependent, the phenomenology resembles that of a generic Higgs portal
dark matter scheme.Comment: 12 pages, final version, published in JHE
The Golden Ratio Prediction for the Solar Angle from a Natural Model with A5 Flavour Symmetry
We formulate a consistent model predicting, in the leading order
approximation, maximal atmospheric mixing angle, vanishing reactor angle and
tan {\theta}_12 = 1/{\phi} where {\phi} is the Golden Ratio. The model is based
on the flavour symmetry A5 \times Z5 \times Z3, spontaneously broken by a set
of flavon fields. By minimizing the scalar potential of the theory up to the
next-to-leading order in the symmetry breaking parameter, we demonstrate that
this mixing pattern is naturally achieved in a finite portion of the parameter
space, through the vacuum alignment of the flavon fields. The leading order
approximation is stable against higher-order corrections. We also compare our
construction to other models based on discrete symmetry groups.Comment: 28 pages, 2 figures. Minor changes, references added. Corrected typos
in Appendix A. Version appeared on JHE
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