189 research outputs found
Large Solar Neutrino Mixing in an Extended Zee Model
The Zee model, which employs the standard Higgs scalar () with its
duplicate () and a singly charged scalar (), can utilize two
global symmetries associated with the conservation of the numbers of and
, , where coincides
with the hypercharge while () is a new
conserved charge, which is identical to for the left-handed
leptons. Charged leptons turn out to have - and - mixing
masses, which are found to be crucial for the large solar neutrino mixing. In
an extended version of the Zee model with an extra triplet Higgs scalar (s),
neutrino oscillations are described by three steps: 1) the maximal atmospheric
mixing is induced by democratic mass terms supplied by with =2 that can
initiate the type II seesaw mechanism for the smallness of these masses; 2) the
maximal solar neutrino mixing is triggered by the creation of radiative masses
by with = 0; 3) the large solar neutrino mixing is finally induced by
a - mixing arising from the rotation of the radiative mass
terms as a result of the diagonalization that converts - and -
mixing masses into the electron mass.Comment: RevTex, 10 pages including one figure page, to be published in Int.
J. Mod. Phys. A (2002
Neutrino Mass Textures with Maximal CP Violation
We have found three types of neutrino mass textures, which give maximal
CP-violation as well as maximal atmospheric neutrino mixing. These textures are
described by six real mass parameters: one specified by two complex flavor
neutrino masses and two constrained ones and the others specified by three
complex flavor neutrino masses. In each texture, we calculate mixing angles and
masses as well as Majorana CP phases.Comment: 10 pages, RevTex, no figures, references updated, version to appear
in Phys. Rev.
Quartic Gauge Boson Couplings and Tree Unitarity in the SU(3)_C X SU(3)_L X U(1)_N Models
The quartic gauge boson couplings in the models are presented. We find that the couplings of four {\it
differrent} gauge bosons may have unusual Lorentz structure and the couplings
sastify the tree unitarity requirement at high energy limit.Comment: 13 pages, Latex, axodraw.st
Can the Zee Model Explain the Observed Neutrino Data?
The eigenvalues and mixing angles in the Zee model are investigated
parameter-independently. When we require |\Delta m^2_{12}/\Delta m^2_{23}| \ll
1 in order to understand the solar and atmospheric data simultaneously, the
only solution is one which gives bi-maximal mixing. It is pointed out that the
observed values \sin^2 2\theta_{solar} \simeq 0.66 in the MSW LMA solution
cannot be explained within the framework of the Zee model, because we derive a
severe constraint on the value of \sin^2 2 \theta_{solar}, \sin^2 2
\theta_{solar} \geq 1 -(1/16)(\Delta m^2_{solar}/\Delta m^2_{atm})^2.Comment: Latex file, 10 pages, 1 figure, explanations and references added,
typos corrected, to be published in Phys.Rev.
Quark Mixing from Mass Matrix Model with Flavor 2 (\leftrightarrow) 3 Symmetry
We consider an universal mass matrix model which has a seesaw-invariant
structure with the most general texture based on flavor 2 (\leftrightarrow) 3
symmetry common to all quarks and leptons. The CKM quark mixing matrix of the
model is analyzed. It is shown that the model is consistent with all the
experimental data of quark mixings by tuning free parameters of the model. We
also show that the values of parameters of the present model consistent with
the experimental data are not far from the ones of the mass matrix model with a
vanishing (1,1) element.Comment: 15 pages, 2 figure
Minimal Scalar Sector of 3-3-1 Models without Exotic Electric Charges
We study the minimal set of Higgs scalars, for models based on the local
gauge group which do not contain
particles with exotic electric charges. We show that only two Higgs
triplets are needed in order to properly break the symmetry. The exact
tree-level scalar mass matrices resulting from symmetry breaking are calculated
at the minimum of the most general scalar potential, and the gauge bosons are
obtained, together with their couplings to the physical scalar fields. We show
how the scalar sector introduced is enough to produce masses for fermions in a
particular model which is an subgroup. By using experimental results we
constrain the scale of new physics to be above 1.3 TeV.Comment: LaTeX, 22 pages, 1 figure include
Deviation from tri-bimaximal mixings in two types of inverted hierarchical neutrino mass models
An attempt is made to explore the possibility for deviations of solar mixing
angle () from tri-bimaximal mixings, without sacrificing the
predictions of maximal atmospheric mixing angle () and zero
reactor angle (). We find that the above conjecture can be
automatically realised in the inverted hierarchical neutrino mass model having
2-3 symmetry, in the basis where charged lepton mass matrix is diagonal. For
the observed ranges of and \bigtriangleup m^2_{23],
we calculate the predictions on for
different input values of the parameters in the neutrino mass matrix. We also
observe a possible crossing over from one type of inverted hierarchical model
having same CP parity (Type-IHA) to other type having opposite CP parity
(Type-IHB). Such neutrino mass matrices can be obtained from the canonical
seesaw formula using diagonal form of Dirac neutrino mass matrix and
non-diagonal texture of right-handed Majorana mass matrix, and may have
important implications in model building using discrete as well as non-abelian
symmetry groups.Comment: 13 pages, 7 figure
Two-loop Radiative Neutrino Mechanism in an Gauge Model
By using the - - symmetry, we construct an
gauge model that provides two-loop radiative neutrino
masses as well as one-loop radiative neutrino masses. The generic smallness of
two-loop neutrino masses leading to compared with one-loop
neutrino masses leading to successfully explains by invoking the - -
breaking. The Higgs scalar () that initiates radiative mechanisms is
unified into a Higgs triplet together with the standard Higgs scalar (,
) to form (, , ), which calls for three families
of lepton triplets: (, , ) (i = 1,2,3), where
denote heavy neutral leptons. The two-loop radiative mechanism is
found possible by introducing a singly charged scalar, which couples to
(i,j = 2,3).Comment: with 10 pages, revtex, including 2 figures, accepted for publication
in Phys. Rev. D (with undefined latex citation indices removed
Escape from washing out of baryon number in a two-zero-texture general Zee model compatible with the large mixing angle MSW solution
We propose a two-zero-texture general Zee model, compatible with the large
mixing angle Mikheyev-Smirnov-Wolfenstein solution. The washing out of the
baryon number does not occur in this model for an adequate parameter range. We
check the consistency of a model with the constraints coming from flavor
changing neutral current processes, the recent cosmic microwave background
observation, and the Z-burst scenario.Comment: 22 pages, 2 eps figures, Type set revtex
Lepton Masses from a TeV Scale in a 3-3-1 Model
In this work, using the fact that in 3-3-1 models the same leptonic bilinear
contributes to the masses of both charged leptons and neutrinos, we develop an
effective operator mechanism to generate mass for all leptons. The effective
operators have dimension five for the case of charged leptons and dimension
seven for neutrinos. By adding extra scalar multiplets and imposing the
discrete symmetry we are able to generate realistic textures
for the leptonic mixing matrix. This mechanism requires new physics at the TeV
scale.Comment: RevTex, 13 pages. Extended version to be published in Physical Review
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