36 research outputs found
A Possible Link between the Electroweak Phase Transition and the Dark Matter of the Universe
A possible connection between the dark matter and strong first order electroweak phase transition,
which is an essential ingredient of the electroweak baryogenesis, has been explored in this thesis.
It is shown that the extension of the Standard Model's minimal Higgs sector with an
inert scalar doublet can provide light dark matter candidate
and simultaneously induce a strong first order phase transition.
There is however no symmetry reason to prevent the
extension using scalars with higher representations. Therefore, by
making random scans over the models' parameters, we show,
in the light of electroweak physics constraints, strong first
order electroweak phase transition and the possibility of having a
sub-TeV cold dark matter candidate, that the
higher representations are rather disfavored compared to the inert
doublet. This is done by computing generic perturbativity
behavior and impact on electroweak phase transitions of higher
representations in comparison with the inert doublet model. Explicit
phase transition and cold dark matter phenomenology within the context
of the inert triplet and quartet representations are used for detailed
illustrations
Gravitational Properties of the Proca Field
We study various properties of a Proca field coupled to gravity through
minimal and quadrupole interactions, described by a two-parameter family of
Lagrangians. St\"uckelberg decomposition of the effective theory spells out its
model-dependent ultraviolet cutoff, parametrically larger than the Proca mass.
We present pp-wave solutions that the model admits, consider linear
fluctuations on such backgrounds, and thereby constrain the parameter space of
the theory by requiring null-energy condition and the absence of negative time
delays in high-energy scattering. We briefly discuss the positivity
constraintsderived from unitarity and analyticity of scattering
amplitudesthat become ineffective in this regard.Comment: 23 pages, revised positivity-bound analysis, references adde
Gamma rays from Dark Matter Annihilation in Three-loop Radiative Neutrino Mass Generation Models
We present the Sommerfeld enhanced Dark Matter (DM) annihilation into gamma
ray for a class of three-loop radiative neutrino mass models with large
electroweak multiplets where the DM mass is in O(TeV) range. We show that in
this model, the DM annihilation rate becomes more prominent for larger
multiplets and it is already within the reach of currently operating Imaging
Atmospheric Cherenkov telescopes (IACTs), High Energy Stereoscopic System
(H.E.S.S.). Furthermore, Cherenkov Telescope Array (CTA), which will begin
operating in 2030, will improve this sensitivity by a factor of
and may exclude a large portion of parameter space of this
radiative neutrino mass model with larger electroweak multiplet. This implies
that the only viable option is the model with lowest electroweak multiplets
i.e. singlets of where the DM annihilation rate is not Sommerfeld
enhanced and hence it is not yet constrained by the indirect detection limits
from H.E.S.S. or future CTA.Comment: 12 pages, 7 figure
Nested Radiative Seesaw Masses for Dark Matter and Neutrinos
The scotogenic model of neutrino mass is modified so that the dark Majorana
fermion singlet which makes the neutrino massive is itself generated in one
loop. This is accomplished by having lepton symmetry softly broken to
in the scalar sector by a unique quadratic term. It is shown that is
a viable freeze-in dark-matter candidate through Higgs decay.Comment: 11 pages, 6 figure
Probing Zee-Babu states at Muon Colliders
The Zee-Babu model is a minimal realization of radiative neutrino mass
generation mechanism at the two-loop level. We study the phenomenology of this
model at future multi-TeV muon colliders. After imposing all theoretical and
low-energy experimental constraints on the model parameters, we find that the
Zee-Babu states are expected not to reside below the TeV scale, making it
challenging to probe them at the LHC. We first analyze the production rates for
various channels, including multi singly-charged and/or doubly-charged scalars
at muon colliders. For concreteness, we study several benchmark points that
satisfy neutrino oscillation data and other constraints and find that most
channels have large production rates. We then analyze the discovery reach of
the model using two specific channels: the pair production of singly- and
doubly-charged scalars. For the phenomenologically viable scenarios considered
in this study, charged scalars with masses up to -- TeV can be
probed for the center-of-mass energy of TeV and total luminosity of
.Comment: 27 pages, 10 figures and 5 table