521 research outputs found
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
Neutrino masses and mixing from S4 flavor twisting
We discuss a neutrino mass model based on the S4 discrete symmetry where the
symmetry breaking is triggered by the boundary conditions of the bulk
right-handed neutrino in the fifth spacial dimension. While the symmetry
restricts bare mass parameters to flavor-diagonal forms, the viable mixing
angles emerge from the wave functions of the Kaluza-Klein modes which carry
symmetry breaking effect. The magnitudes of the lepton mixing angles,
especially the reactor angle is related to the neutrino mass patterns and the
model will be tested in future neutrino experiments, e.g., an early (late)
discovery of the reactor angle favors the normal (inverted) hierarchy. The size
of extra dimension has a connection to the possible mass spectrum; a small
(large) volume corresponds to the normal (inverted) mass hierarchy.Comment: 22 pages, 3 figures; added references for section
Principal series of finite subgroups of SU(3)
We attempt to give a complete description of the "exceptional" finite
subgroups Sigma(36x3), Sigma(72x3) and Sigma(216x3) of SU(3), with the aim to
make them amenable to model building for fermion masses and mixing. The
information on these groups which we derive contains conjugacy classes, proper
normal subgroups, irreducible representations, character tables and tensor
products of their three-dimensional irreducible representations. We show that,
for these three exceptional groups, usage of their principal series, i.e.
ascending chains of normal subgroups, greatly facilitates the computations and
illuminates the relationship between the groups. As a preparation and testing
ground for the usage of principal series, we study first the dihedral-like
groups Delta(27) and Delta(54) because both are members of the principal series
of the three groups discussed in the paper.Comment: 43 pages, no figures; typos corrected, clarifications and references
added, version matches publication in J. Phys.
Novel Technique for Ultra-sensitive Determination of Trace Elements in Organic Scintillators
A technique based on neutron activation has been developed for an extremely
high sensitivity analysis of trace elements in organic materials. Organic
materials are sealed in plastic or high purity quartz and irradiated at the
HFIR and MITR. The most volatile materials such as liquid scintillator (LS) are
first preconcentrated by clean vacuum evaporation. Activities of interest are
separated from side activities by acid digestion and ion exchange. The
technique has been applied to study the liquid scintillator used in the KamLAND
neutrino experiment. Detection limits of <2.4X10**-15 g 40K/g LS, <5.5X10**-15
g Th/g LS, and <8X10**-15 g U/g LS have been achieved.Comment: 16 pages, 3 figures, accepted for publication in Nuclear Instruments
and Methods
Direct and Indirect Detection of Dark Matter in D6 Flavor Symmetric Model
We study a fermionic dark matter in a non-supersymmetric extension of the
standard model with a family symmetry based on D6xZ2xZ2. In our model, the
final state of the dark matter annihilation is determined to be e+ e- by the
flavor symmetry, which is consistent with the PAMELA result. At first, we show
that our dark matter mass should be within the range of 230 GeV - 750 GeV in
the WMAP analysis combined with mu to e gamma constraint. Moreover we
simultaneously explain the experiments of direct and indirect detection, by
simply adding a gauge and D6 singlet real scalar field. In the direct detection
experiments, we show that the lighter dark matter mass ~ 230 GeV and the
lighter standard model Higgs boson ~ 115 GeV is in favor of the observed bounds
reported by CDMS II and XENON100. In the indirect detection experiments, we
explain the positron excess reported by PAMELA through the Breit-Wigner
enhancement mechanism. We also show that our model is consistent with no
antiproton excess suggested by PAMELA.Comment: 20 pages, 9 figures, 2 tables, accepted version for publication in
European Physical Journal
Geometrical CP violation in multi-Higgs models
We introduce several methods to obtain calculable phases with geometrical
values that are independent of arbitrary parameters in the scalar potential.
These phases depend on the number of scalars and on the order of the discrete
non-Abelian group considered. Using these methods we present new geometrical CP
violation candidates with vacuum expectation values that must violate CP (the
transformation that would make them CP conserving is not a symmetry of the
potential). We also extend to non-renormalisable potentials the proof that more
than two scalars are needed to obtain these geometrical CP violation
candidates.Comment: 8 pages, 2 figures. v2: table added, accepted by JHE
Abelian Chern-Simons Vortices and Holomorphic Burgers' Hierarchy
The Abelian Chern-Simons Gauge Field Theory in 2+1 dimensions and its
relation with holomorphic Burgers' Hierarchy is considered. It is shown that
the relation between complex potential and the complex gauge field as in
incompressible and irrotational hydrodynamics, has meaning of the analytic
Cole-Hopf transformation, linearizing the Burgers Hierarchy in terms of the
holomorphic Schr\"odinger Hierarchy. Then the motion of planar vortices in
Chern-Simons theory, appearing as pole singularities of the gauge field,
corresponds to motion of zeroes of the hierarchy. Using boost transformations
of the complex Galilean group of the hierarchy, a rich set of exact solutions,
describing integrable dynamics of planar vortices and vortex lattices in terms
of the generalized Kampe de Feriet and Hermite polynomials is constructed. The
results are applied to the holomorphic reduction of the Ishimori model and the
corresponding hierarchy, describing dynamics of magnetic vortices and
corresponding lattices in terms of complexified Calogero-Moser models.
Corrections on two vortex dynamics from the Moyal space-time non-commutativity
in terms of Airy functions are found.Comment: 15 pages, talk presented in Workshop `Nonlinear Physics IV: Theory
and Experiment`, 22-30 June 2006, Gallipoli, Ital
Towards Minimal S4 Lepton Flavor Model
We study lepton flavor models with the flavor symmetry. We construct
simple models with smaller numbers of flavon fields and free parameters, such
that we have predictions among lepton masses and mixing angles. The model with
a triplet flavon is not realistic, but we can construct realistic models
with two triplet flavons, or one triplet and one doublet flavons.Comment: 18 pages, 4 figures, references are adde
Discrete symmetries and models of flavor mixing
Evidences of a discrete symmetry behind the pattern of lepton mixing are
analyzed. The program of "symmetry building" is outlined. Generic features and
problems of realization of this program in consistent gauge models are
formulated. The key issues include the flavor symmetry breaking, connection of
mixing and masses, {\it ad hoc} prescription of flavor charges, "missing"
representations, existence of new particles, possible accidental character of
the TBM mixing. Various ways are considered to extend the leptonic symmetries
to the quark sector and to reconcile them with Grand Unification. In this
connection the quark-lepton complementarity could be a viable alternative to
TBM. Observational consequences of the symmetries and future experimental tests
of their existence are discussed.Comment: 14 pages, 5 figures. Talk given at the Symposium "DISCRETE 2010", 6 -
11 December 2010, La Sapienza, Rome, Ital
The Cabibbo Angle in a Supersymmetric D14 Model
We construct a supersymmetric model with the flavor symmetry D14 in which the
CKM matrix element |V_{ud}| can take the value |V_{ud}| =cos (pi/14) = 0.97493
implying that the Cabibbo angle theta_C is sin (theta_C) = |V_{us}| = sin
(pi/14) = 0.2225. These values are very close to those observed in experiments.
The value of |V_{ud}| (theta_C) is based on the fact that different Z2
subgroups of D14 are conserved in the up and down quark sector. In order to
achieve this, D14 is accompanied by a Z3 symmetry. The spontaneous breaking of
D14 is induced by flavons, which are scalar gauge singlets. The quark mass
hierarchy is partly due to the flavor group D14 and partly due to a
Froggatt-Nielsen symmetry U(1)_{FN} under which only the right-handed quarks
transform. The model is completely natural in the sense that the hierarchies
among the quark masses and mixing angles are generated with the help of
symmetries. The issue of the vacuum alignment of the flavons is solved up to a
small number of degeneracies, leaving four different possible values for
|V_{ud}|. Out of these, only one of them leads to a phenomenological viable
model. A study of the Z2 subgroup breaking terms shows that the results
achieved in the symmetry limit are only slightly perturbed. At the same time
they allow |V_{ud}| (theta_C) to be well inside the small experimental error
bars.Comment: 1+24 page
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