352 research outputs found
Supersymmetric Extension of the Minimal Dark Matter Model
The minimal dark matter model is given a supersymmetric extension. A super
SU(2)L quintuplet is introduced with its fermionic neutral component still
being the dark matter, the dark matter particle mass is about 19.7 GeV. Mass
splitting among the quintplet due to supersymmetry particles is found to be
negligibly small compared to the electroweak corrections. Other properties of
this supersymmetry model are studied, it has the solutions to the PAMELA and
Fermi-LAT anomaly, the predictions in higher energies need further experimental
data to verify.Comment: 14 pages, 7 figures, accepted for publication in Chinese Physics C,
typos correcte
Novel TeV-scale seesaw mechanism with Dirac mediators
We propose novel tree level seesaw mechanism with TeV-scale vectorlike Dirac
mediators that produce Majorana masses of the known neutrinos. The gauge
quantum number assignment to the Dirac mediators allows them to belong to a
weak triplet and a five-plet of nonzero hypercharge. The latter leads to new
seesaw formula m_\nu ~ v^6/M^5, so that the empirical masses m_\nu ~ 10^{-1} eV
can be achieved by M ~ TeV new states. There is a limited range of the
parameter space with M < a few 100 GeV where the tree level contribution
dominates over the respective loop contributions and the proposed mechanism is
testable at the LHC. We discuss specific signatures for Dirac type heavy
leptons produced by Drell-Yan fusion at the LHC.Comment: 10 pages, 1 figure, version corresponding to PL
Electroweak two-loop contribution to the mass splitting within a new heavy SU(2) fermion multiplet
New heavy particles in an SU(2)_L multiplet, sometimes introduced in
extensions of the standard model, have highly degenerate tree-level mass M if
their couplings to the Higgs bosons are very small or forbidden. However, loop
corrections may generate the gauge-symmetry-breaking mass splitting within the
multiplet, which does not vanish in the large M limit due to the threshold
singularity. We calculate the electroweak contribution to the mass splitting
for a heavy fermion multiplet, to the two-loop order. Numerically, two-loop
electroweak contributions are typically O(MeV).Comment: 14 pages, style changed, analytic forms of two-loop functions adde
Connecting Dark Energy to Neutrinos with an Observable Higgs Triplet
To connect the scalar field (acceleron) responsible for dark energy to
neutrinos, the usual strategy is to add unnaturally light neutral singlet
fermions (right-handed neutrinos) to the Standard Model. A better choice is
actually a Higgs triplet, through the coupling of the acceleron to the
trilinear Higgs triplet-double-doublet interaction. This hypothesis predicts an
easily observable doubly-charged Higgs boson at the forthcoming Large Hadron
Collider (LHC).Comment: 9 page
Dark Matter: The Leptonic Connection
Recent observatons of high-energy positrons and electrons by the PAMELA and
ATIC experiments may be an indication of the annihilation of dark matter into
leptons and not quarks. This leptonic connection was foreseen already some
years ago in two different models of radiative neutrino mass. We discuss here
the generic interactions (nu eta^0 - l eta^+) chi and l^c zeta^- chi^c which
allow this to happen, where chi and/or chi^c are fermionic dark-matter
candidates. We point out in particular the importance of chi chi to l^+ l^-
gamma to both positron and gamma-ray signals within this framework.Comment: 4 pages, 5 figures. v2: PLB versio
Electroweak Symmetry Breaking induced by Dark Matter
The mechanism behind Electroweak Symmetry Breaking (EWSB) and the nature of
dark matter (DM) are currently among the most important issues in high energy
physics. Since a natural dark matter candidate is a weakly interacting massive
particle or WIMP, with mass around the electroweak scale, it is clearly of
interest to investigate the possibility that DM and EWSB are closely related.
In the context of a very simple extension of the Standard Model, the Inert
Doublet Model, we show that dark matter could play a crucial role in the
breaking of the electroweak symmetry. In this model, dark matter is the
lightest component of an inert scalar doublet. The coupling of the latter with
the Standard Model Higgs doublet breaks the electroweak symmetry at one-loop,
"a la Coleman-Weinberg". The abundance of dark matter, the breaking of the
electroweak symmetry and the constraints from electroweak precision
measurements can all be accommodated by imposing an (exact or approximate)
custodial symmetry.Comment: 4 pages, no figure, one tabl
Parameters in a Class of Leptophilic Dark Matter Models from PAMELA, ATIC and FERMI
In this work we study a class of leptophilic dark matter models, where the
dark matter interacts with the standard model particles via the
gauge boson, to explain the excess in cosmic rays
observed by ATIC and PAMELA experiments, and more recently by Fermi experiment.
There are three types of models: a) , b)
, and c) . Although ATIC or Fermi
data is consistent with PAMELA data separately, ATIC and Fermi data do not
agree with each other. We therefore aim to identify which of the three models
can explain which data set better. We find that models a) and b) can give
correct dark matter relic density and explain the ATIC and PAMELA data
simultaneously recur to the Breit-Wigner enhancement. Whereas model c) with a
larger mass can explain Fermi and PAMELA data simultaneously. In all
cases the model parameters are restricted to narrow regions. Future improved
data will decide which set of data are correct and also help to decide the
correct dark matter model.Comment: Latex 15 pages with 5 figures. Modified to include discussions of
recent Fermi data on the leptophilic models studied in this paper. Title also
modifie
A simple inert model solves the little hierarchy problem and provides a dark matter candidate
We discuss a minimal extension to the standard model in which two singlet
scalar states that only interacts with the Higgs boson is added. Their masses
and interaction strengths are fixed by the two requirements of canceling the
one-loop quadratic corrections to the Higgs boson mass and providing a viable
dark matter candidate. Direct detection of the lightest of these new states in
nuclear scattering experiments is possible with a cross section within reach of
future experiments.Comment: Finite corrections included. Model modified. Conclusion unchange
Unified picture for Dirac neutrinos, dark matter, dark energy and matter-antimatter asymmetry
We propose a unified scenario to generate the masses of Dirac neutrinos and
cold dark matter at the TeV scale, understand the origin of dark energy and
explain the matter-antimatter asymmetry of the universe. This model can lead to
significant impact on the Higgs searches at LHC.Comment: 5 pages, 3 figures. Title changed. Abstract, introduction and summary
revised. References added. Model and conclusion unchange
Searching for Secluded Dark Matter via Direct Detection of Recoiling Nuclei as well as Low Energy Electrons
Motivated by recent cosmic ray experimental results there has been a
proposition for a scenario where a secluded dark matter particle annihilates,
primarily, into Standard Model leptons through a low mass mediator particle. We
consider several varieties of this scenario depending on the type of mixing
among gauge bosons and we study the implications in novel direct dark matter
experiments for detecting low energy recoiling electrons. We find significant
event rates and time modulation effects, especially in the case where the
mediator is massless, that may be complementary to those from recoiling nuclei.Comment: 27 pages, references added, published versio
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