425 research outputs found
Renormalizable Model for Neutrino Mass, Dark Matter, Muon and 750 GeV Diphoton Excess
We discuss a possibility to explain the 750 GeV diphoton excess observed at
the LHC in a three-loop neutrino mass model which has a similar structure to
the model by Krauss, Nasri and Trodden. Tiny neutrino masses are naturally
generated by the loop effect of new particles with their couplings and masses
to be of order 0.1-1 and TeV, respectively. The lightest right-handed neutrino,
which runs in the three-loop diagram, can be a dark matter candidate. In
addition, the deviation in the measured value of the muon anomalous magnetic
moment from its prediction in the standard model can be compensated by one-loop
diagrams with exotic multi-charged leptons and scalar bosons. For the diphoton
event, an additional isospin singlet real scalar field plays the role to
explain the excess by taking its mass of 750 GeV, where it is produced from the
gluon fusion production via the mixing with the standard model like Higgs
boson. We find that the cross section of the diphoton process can be obtained
to be a few fb level by taking the masses of new charged particles to be about
375 GeV and related coupling constants to be order 1.Comment: 17 pages, 8 figure
Flavour Dependent Gauged Radiative Neutrino Mass Model
We propose a one-loop induced radiative neutrino mass model with anomaly free
flavour dependent gauge symmetry: minus symmetry
. A neutrino mass matrix satisfying current experimental data
can be obtained by introducing a weak isospin singlet scalar boson that breaks
symmetry, an inert doublet scalar field, and three
right-handed neutrinos in addition to the fields in the standard model. We find
that a characteristic structure appears in the neutrino mass matrix: two-zero
texture form which predicts three non-zero neutrino masses and three non-zero
CP-phases from five well measured experimental inputs of two squared mass
differences and three mixing angles. Furthermore, it is clarified that only the
inverted mass hierarchy is allowed in our model. In a favored parameter set
from the neutrino sector, the discrepancy in the muon anomalous magnetic moment
between the experimental data and the the standard model prediction can be
explained by the additional neutral gauge boson loop contribution with mass of
order 100 MeV and new gauge coupling of order .Comment: 15 pages, 1 figure, 2 table
Electron/Muon Specific Two Higgs Doublet Model
We discuss two Higgs doublet models with a softly-broken discrete
symmery, where the mass matrix for charged-leptons is predicted
as the diagonal form in the weak eigenbasis of lepton fields. Similar to an
introduction of symmetry, the tree level flavor changing neutral
current can be forbidden by imposing the symmetry to the model.
Under the symmetry, there are four types of Yukawa interactions
depending on the charge assignment to right-handed fermions. We
find that extra Higgs bosons can be muon and electron specific in one of four
types of the Yukawa interaction. This property does not appear in any other two
Higgs doublet models with a softly-broken symmetry. We discuss
the phenomenology of the muon and electron specific Higgs bosons at the Large
Hadron Collider; namely we evaluate allowed parameter regions from the current
Higgs boson search data and discovery potential of such a Higgs boson at the 14
TeV run.Comment: 17 pages, 5 figures, 6 tables; version published in Nuclear Physics
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