25 research outputs found
Scale-Invariant Two Component Dark Matter
We study a scale invariant extension of the standard model which can explain
simultaneously dark matter and the hierarchy problem. In our set-up, we
introduce a scalar and a spinor as two-component dark matter in addition to
scalon field as a mediator. Interesting point about our model is that due to
scale invariant conditions, compared to other two-component dark matter models,
it has lower independent parameters. Possible astrophysical and laboratory
signatures of two-component dark matter candidate are explored and it is shown
that the most contribution of observed relic density of dark matter can be
determined by spinor dark matter. Detectability of these dark matter particles
is studied and the direct and invisible Higgs decay experiments are used to
rule out part of the parameter space of the model. In addition, the dark matter
self-interactions are considered and shown that their contribution saturate
this constraint in the resonant regions.Comment: 22 pages, 14 figure
Impact of Torsion Space-Time on observables at Hadron Colliders
Starting from the effective torsion space-time model, we study its effects on
the top pair production cross section at hadron colliders. We also study the
effect of this model on top pair asymmetries at the Tevatron and the LHC. We
find that torsion space-time can explain forward-backward asymmetry according
to measured anomaly at Tevatron. We find an allowed region in the parameters
space which can satisfy simultaneously all observables measured at
Tevatron and LHC.Comment: 17 pages, 6 figures. arXiv admin note: substantial text overlap with
arXiv:1207.064
Conformal vector dark matter and strongly first-order electroweak phase transition
We study a conformal version of the Standard Model (SM), which apart from SM
sector, containing a dark sector with a vector dark matter
candidate and a scalar field (scalon). In this model the dark sector couples to
the SM sector via a Higgs portal. The theory is scale-invariant in lowest
order, therefore the spontaneous symmetry breaking of scale invariance entails
the existence of a scalar particle, scalon, with vanishing zeroth-order mass.
However, one-loop corrections break scale invariance, so they give mass to the
scalon. Because of the scale invariance, our model is subjected to constraints
which remove many of the free parameters. We put constraints to the two
remaining parameters from the Higgs searches at the LHC, dark matter relic
density and dark matter direct detection limits by PandaX-II. The viable mass
region for dark matter is about 1-2 TeV. We also obtain the finite temperature
one-loop effective potential of the model and demonstrate that finite
temperature effects, for the parameter space constrained by dark matter relic
density, induce a strongly first-order electroweak phase transition.Comment: 27 pages, 7 figures, a few clarifications added, references updated,
version published in JHE
Probing the top quark chromoelectric and chromomagnetic dipole moments in single top -channel at the LHC
We study the effects of chromoelectric and chromomagnetic dipole moments
(CEDM and CMDM) on the production cross section of single top -channel at
the LHC based on the effective Lagrangian approach. We show that the impact of
CEDM and CMDM could be large. Using the experimental measurement of the
-channel cross section, constraints on CEDM and CMDM are extracted. These
constraints are comparable with the ones obtained from the top pair analysis.Comment: 13 pages, 4 figure
Gravitational wave effects and phenomenology of a two-component dark matter model
We study an extension of the Standard Model (SM) which could have two
candidates for dark matter (DM) including a Dirac fermion and a Vector Dark
Matter (VDM) under new gauge group in the hidden sector. The model is
classically scale invariant and the electroweak symmetry breaks because of the
loop effects. We investigate the parameter space allowed by current
experimental constraints and phenomenological bounds. We probe the parameter
space of the model in the mass range GeV and
GeV. It has been shown that there are many points in this mass range that are
in agreement with all phenomenological constraints. The electroweak phase
transition have been discussed and shown that there is region in the parameter
space of the model consistent with DM relic density and direct detection
constraints, while at the same time can lead to first order electroweak phase
transition. The gravitational waves produced during the phase transition could
be probed by future space-based interferometers such as LISA and BBO.Comment: 28 pages, 11 figure