81 research outputs found
Radiative Neutrino Model with Inert Triplet Scalar
We study a one-loop induced radiative neutrino model with an inert isospin
triplet scalar field, in which we discuss current neutrino oscillation data,
lepton flavor violations, muon anomalous magnetic moment, and a dark matter
candidate. We show global analysis combining all the constraints, and briefly
mention another possibility.Comment: 21 pages, 3 figures, 3 tables, references added. Accepted version for
publication in Physical Review D, discussion of mu-e conversion is added and
the part of relic density are modified. arXiv admin note: text overlap with
arXiv:1509.0406
Two-loop Neutrino Model with Exotic Leptons
We propose a two-loop induced neutrino mass model, in which we show some
bench mark points to satisfy the observed neutrino oscillation, the constraints
of lepton flavor violations, and the relic density in the co-annihilation
system satisfying the current upper bound on the spin independent scattering
cross section with nuclei. We also discuss new sources of muon anomalous
magnetic moment.Comment: 20 pages, 1 figure, 4 table
X-ray line in Radiative Neutrino Model with Global Symmetry
We study a three loop induced radiative neutrino model with global
symmetry at TeV scale, in which we consider two component dark matter
particles. We discuss the possibility to explain the X-ray line signal at about
3.55 keV recently reported by XMN-Newton X-ray observatory using data of
various galaxy clusters and Andromeda galaxy. Subsequently, we also discuss to
show that sizable muon anomalous magnetic moment, a discrepancy of the
effective number of neutrino species 0.39, and
scattering cross section detected by direct detection searches can be derived.Comment: 14 pages, 3 figures, 1 table; version accepted for publication in
Physical Review
Neutrinophilic two Higgs doublet model with global symmetry
We propose a neutrinophilic two-Higgs-doublet model, where the vacuum
expectation value (VEV) of the second Higgs doublet is only induced at one-loop
level via several neutral fermions. Thus, the masses of active neutrinos
arising from the Higgs doublets are naturally small via such a tiny VEV. We
discuss various phenomenology of the model, including the neutrino masses and
oscillations, bounds on non-unitarity, lepton-flavor violations, the oblique
parameters, the muon anomalous magnetic moment, the GeV-scale sterile neutrino
candidate arising from the tiny VEV, and collider signatures. We finally
discuss the possibility of detecting the sterile neutrino suggested in the
experiment of Future Circular Collider (FCC).Comment: 20 pages, 3 figure, 2 tables; reference added; figures and
discussions are adde
A Two Loop Radiative Neutrino Model
We explore the possibility to explain a bosonic dark matter candidate with a
gauge singlet inside the loop to generate the neutrino mass matrix at two-loop
level. The mass matrix is suppressed by a small mixing that comes from the
bound on {direct detection experiments of the dark matter, and equivalent of
the three-loop neutrino model due to the small mixing between neutral inert
bosons. Here, our setup is} the Zee-Babu type scenario with discrete
symmetry, in which we consider the neutrino oscillation data, lepton flavor
violations, muon , conversion rate, lepton flavor-changing and
conserving boson decay and bosonic dark matter candidate.Comment: 16 pages, 5 figures, 2 tables; reference added, typos corrected; the
model extended, figures changed, title changed, version accepted for
publication in Nuclear Physics
Nonthermal dark matter models and signals
Many experiments exploring weakly interacting massive particles (WIMPs) such
as direct, indirect and collider searches have been carried out until now.
However, a clear signal of a WIMP has not been found yet and it makes us to
suspect that WIMPs are questionable as a dark matter candidate. Taking into
account this situation, we propose two models in which dark matter relic
density is produced by decay of a metastable particle. In the first model, the
metastable particle is a feebly interacting massive particle, which is the
so-called FIMP produced by freeze-in mechanism in the early universe. In the
second model, the decaying particle is thermally produced the same as the usual
WIMP. However decay of the particle into dark matter is led by a higher
dimensional operator. As a phenomenologically interesting feature of nonthermal
dark matter discussed in this paper, a strong sharp gamma-ray emission as an
indirect detection signal occurs due to internal bremsstrahlung, although some
parameter space has already been ruled out by this process. Moreover combining
other experimental and theoretical constraints such as dark matter relic
density, big bang nucleosynthesis, collider, gamma-rays and perturbativity of
couplings, we discuss the two nonthermal DM models.Comment: 20 pages, 3 figures, 2 tables, version to appear in PR
Higgs Triplet Model with Classically Conformal Invariance
We discuss an extension of the minimal Higgs triplet model with a classically
conformal invariance and with a gauged symmetry. In our scenario,
tiny masses of neutrinos are generated by a hybrid contribution from the type-I
and type-II seesaw mechanisms. The shape of the Higgs potential at low energies
is determined by solving one-loop renormalization group equations for all the
scalar quartic couplings with a set of initial values of parameters at the
Planck scale. We find a successful set of the parameters in which the
symmetry is radiatively broken via the Coleman-Weinberg mechanism
at the (10) TeV scale, and the electroweak symmetry breaking is also
triggered by the breaking. Under this configuration, we can
predict various low energy observables such as the mass spectrum of extra Higgs
bosons, and the mixing angles. Furthermore, using these predicted mass
parameters, we obtain upper limits on Yukawa couplings among an isospin triplet
Higgs field and lepton doublets from lepton flavor violation data.Comment: References adde
Radiative Seesaw Model with Degenerate Majorana Dark Matter
We study a three loop induced neutrino mass model with exotic vector-like
isospin doublet leptons which contain a dark matter candidate. Then we explore
lepton flavor violations, and dark matter physics in co-annihilation system. In
this paper the nearly degenerate Majorana fermion dark matter can naturally be
achieved at the two loop level, while the mass splitting can be larger than
(200) keV which is required from the constraint of the direct
detection search with spin independent inelastic scattering through boson
portal. As a result a monochromatic photon excess, its threshold energy is
greater than (200) keV, is predicted in our model that could be
measured through indirect detection experiments such as INTEGRAL.Comment: 17 pages, 1 figure, 2 table
Three Loop Neutrino Model with Isolated
We propose a three loop radiative neutrino mass scenario with an isolated
doubly charged singlet scalar without couplings to the charged
leptons, while two other singly charged scalars and attach
to them. In this setup, the lepton flavor violation originating from
exchanges is suppressed and the model is less constrained, where
some couplings can take sizable values. As reported in our previous work, the
loop suppression factor at the three loop level would be too strong and
realized neutrino masses in a three loop scenario could be smaller than the
observed minuscule values. The sizable couplings can help us to enhance
neutrino masses without drastically large scalar trilinear couplings appearing
in a neutrino mass matrix, which tends to drive the vacuum stability to become
jeopardized at the one loop level. Now the doubly charged scalar
has less constraint via lepton flavor violation and the vacuum can be quite
stable, and thus a few hundred GeV mass in is possible, which is
within the LHC reach and this model can be tested in the near future. Note that
the other and should be heavy at least around a few TeV. We
suitably arrange the charges of an additional global symmetry, where the
decay constant of the associated Nambu-Goldstone boson can be around a TeV
scale consistently. Also, this model is indirectly limited through a global
analysis on results of the LHC Higgs search and issues on a dark matter
candidate, the lightest Majorana neutrino. After and are
decoupled, this particle couples to the standard model particles only through
two charge parity even scalars in theory and thus information on this scalar
sector is important. Consistent solutions are found, but a part of them is now
on the edge.Comment: 48 pages, 9 figures, 6 tables (v3): published version from PRD, title
changed, typos corrected, new discussions adde
An Septet Scalar Linking to Radiative Neutrino Model
We study a radiative neutrino model with a SU(2) septet scalar with
hypercharge where active neutrino mass is induced at a one-loop level.
Calculating a one-loop diagram, mass matrices for active neutrino is derived.
We also analyze lepton flavor violations, anomalous magnetic moment of muon and
the flavor violating Higgs decay . Then sizable muon and
of could be obtained in our set up.
Furthermore, the collider signature of the septet is discussed where we focus
on quadratically charged scalar at the LHC 14 TeV. We find that it could be
discovered up to TeV mass by searching multi charged lepton signal
events.Comment: 20 pages, 4 figures, 3 tables, references added. arXiv admin note:
text overlap with arXiv:1512.0668
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