723 research outputs found
Parallel Texture Structures with Cofactor Zeros in Lepton Sector
In this paper we investigate the parallel texture structures with cofactor
zeros in the charged lepton and neutrino sectors. The textures can not be
obtained from arbitrary leptonic matrices by making weak basis transformations,
which therefore have physical meaning. The 15 parallel textures are grouped as
4 classes where each class has the same physical implications. It is founded
that one of them is not phenomenological viable and another is equivalent to
the texture zero structures extensively explored in previous literature. Thus
we focus on the other two classes of parallel texture structures and study the
their phenomenological implications. The constraints on the physical variables
are obtained for each class, which are essential for the model selection and
can be measured by future experiments. The model realization is illustrated in
a radiated lepton mass model.Comment: 21 pages, 4 figures. An errors of calculation is corrected,
phenomenology is partly change
Neutrino mass textures with one vanishing minor and two equal cofactors
In this paper, we carry out a numerical and systematic analysis of the
neutrino mass textures, which contain one vanishing minor and an equality
between two cofactors. Among 60 logically possible textures, only eight of them
are excluded for both normal and inverted hierarchy by the current experimental
data at 3\sigma level. We also demonstrate that the future long-baseline
neutrino oscillation experiments, especially for the measurement of \theta 23
mixing angle, will play the important role in the model selection. The
phenomenological implications from neutrinoless double beta decay and the
cosmology observation are also examined. A discussion on the flavor symmetry
realization of the textures is also given.Comment: 18 pages, 2 figure
Naturally Small Dirac Neutrino Mass with Intermediate Multiplet Fields
If neutrinos are Dirac fermions, certain new physics beyond the standard
model should exist to account for the smallness of neutrino mass. With two
additional scalars and a heavy intermediate fermion, in this paper, we
systematically study the general mechanism that can natrally generate the tiny
Dirac neutrino mass at tree and in one-loop level. For tree level models, we
focus on natural ones, in which the additional scalars develop small vacuum
expectation values without fine-tuning. For one-loop level models, we explore
those having dark matter candidates under symmetry. In both cases, we
concentrate on multiplet scalars no larger than quintuplet, and
derive the complete sets of viable models. Phenomenologies, such as lepton
flavor violation, leptogenesis, and LHC signatures are briefly discussed.Comment: 31 pages, 16 figure
The Scotogenic Models for Dirac Neutrino Masses
We construct the one-loop and two-loop scotogenic models for Dirac neutrino
mass generation in the context of extensions of standard model. It
is indicated that the total number of intermediate fermion singlets is uniquely
fixed by anomaly free condition and the new particles may have exotic
charges so that the direct SM Yukawa mass term
and the Majorana mass term
are naturally forbidden. After the spontaneous
breaking of symmetry, the discrete or symmetry
appears as the residual symmetry and give rise to the stability of
intermediated fields as DM candidate. Phenomenological aspects of lepton flavor
violation, DM, leptogenesis and LHC signatures are discussed.Comment: 18 pages, 16 figure
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