168 research outputs found
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
Light Dark Matter Candidate in B-L Gauged Radiative Inverse Seesaw
We study a radiative inverse seesaw model with local B-L symmetry, in which
we extend the neutrino mass structure that is generated through a kind of
inverse seesaw framework to the more generic one than our previous work. We
focus on a real part of bosonic particle as a dark matter and investigate the
features in O(1-80) GeV mass range, reported by the experiments such as CoGeNT
and XENON (2012).Comment: 10 pages, 1 table, 3 figures; version accepted for publication in
European Physical Journal
Universally Leptophilic Dark Matter From Non-Abelian Discrete Symmetry
The positron anomaly recently reported by the cosmic-ray measurements can be
explained by the decaying dark matter scenario, where it decays mainly into
leptons with the lifetime of O(10^26) second. When the dark matter is a
fermionic particle, the lifetime of this order is known to be obtained by a
dimension 6 operator suppressed by the unification scale 10^16 GeV, while such
decay operators do not necessarily involve only leptons. In addition, the
scenario would be spoiled if there exist lower-dimensional operators inducing
the dark matter decay. We show in this letter that a single non-Abelian
discrete symmetry such as A_4 is possible to prohibit all such harmful
(non-leptonically coupled and lower-dimensional) operators. Moreover, the dark
matter decays into charged leptons in a flavor-blind fashion due to the
non-Abelian flavor symmetry, which results in perfect agreements not only with
the PAMELA data but also with the latest Fermi-LAT data reported very recently.
We also discuss some relevance between the discrete symmetry and neutrino
physics.Comment: 13 pages, 2 tables, 1 figur
D6 Family Symmetry and Cold Dark Matter at LHC
We consider a non-supersymmetric extension of the standard model with a
family symmetry based on D6 Z2 Z2, where one of Z2's is exactly conserved. This
Z2 forbids the tree-level neutrino masses and simultaneously ensures the
stability of cold dark matter candidates. From the assumption that cold dark
matter is fermionic we can single out the D6 singlet right-handed neutrino as
the best cold dark mater candidate. We find that an inert charged Higgs with a
mass between 300 and 750 GeV decays mostly into an electron (or a positron)
with a large missing energy, where the missing energy is carried away by the
cold dark matter candidate. This will be a clean signal at LHC.Comment: 20 pages, 7 figure
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