78,871 research outputs found
Non-Abelian Discrete Dark Matter
We consider the minimal model in which dark matter is stabilized by a
non-Abelian discrete symmetry. The symmetry group is taken to be D_3, which is
the smallest non-Abelian finite group. The minimal model contains (nontrivial)
singlet and doublet scalar representations of D_3 which couple to the Standard
Model fields via the Higgs portal. This construction predicts two species of
dark matter over much of the parameter space. Nontrivial interactions under D_3
lead to a novel thermal history of dark matter, while the multi-component
nature of dark matter can be tested by future direct detection experiments.Comment: 12 pages, 6 figure
Bino Dark Matter and Big Bang Nucleosynthesis in the Constrained E6SSM with Massless Inert Singlinos
We discuss a new variant of the E6 inspired supersymmetric standard model
(E6SSM) in which the two inert singlinos are exactly massless and the dark
matter candidate has a dominant bino component. A successful relic density is
achieved via a novel mechanism in which the bino scatters inelastically into
heavier inert Higgsinos during the time of thermal freeze-out. The two massless
inert singlinos contribute to the effective number of neutrino species at the
time of Big Bang Nucleosynthesis, where the precise contribution depends on the
mass of the Z' which keeps them in equilibrium. For example for mZ' > 1300 GeV
we find Neff \approx 3.2, where the smallness of the additional contribution is
due to entropy dilution. We study a few benchmark points in the constrained
E6SSM with massless inert singlinos to illustrate this new scenario.Comment: 24 pages, revised for publication in JHE
Improved bounds on singlet dark matter
We reconsider complex scalar singlet dark matter stabilised by a
symmetry. We refine the stability bounds on the potential and
use constraints from unitarity on scattering at finite energy to place a
stronger lower limit on the direct detection cross section. In addition, we
improve the treatment of the thermal freeze-out by including the evolution of
the dark matter temperature and its feedback onto relic abundance. In the
regions where the freeze-out is dominated by resonant or semi-annihilation, the
dark matter decouples kinetically from the plasma very early, around the onset
of the chemical decoupling. This results in a modification of the required
coupling to the Higgs, which turns out to be at most few per cent in the
semi-annihilation region, thus giving credence to the standard approach to the
relic density calculation in this regime. In contrast, for dark matter mass
just below the Higgs resonance, the modification of the Higgs invisible width
and direct and indirect detection signals can be up to a factor . The
model is then currently allowed at GeV to GeV (depending on the
details of early kinetic decoupling) GeV and at
GeV if the freeze-out is dominated by semi-annihilation. We
show that the whole large semi-annihilation region will be probed by the
near-future measurements at the XENONnT experiment.Comment: 22 pages, 4 figure
The Fraternal WIMP Miracle
We identify and analyze thermal dark matter candidates in the fraternal twin
Higgs model and its generalizations. The relic abundance of fraternal twin dark
matter is set by twin weak interactions, with a scale tightly tied to the weak
scale of the Standard Model by naturalness considerations. As such, the dark
matter candidates benefit from a "fraternal WIMP miracle," reproducing the
observed dark matter abundance for dark matter masses between 50 and 150 GeV.
However, the couplings dominantly responsible for dark matter annihilation do
not lead to interactions with the visible sector. The direct detection rate is
instead set via fermionic Higgs portal interactions, which are likewise
constrained by naturalness considerations but parametrically weaker than those
leading to dark matter annihilation. The predicted direct detection cross
section is close to current LUX bounds and presents an opportunity for the next
generation of direct detection experiments.Comment: 22 pages, 6 figures. v2: Relic abundance calculations revised and
improved, citations added. Conclusions largely unchanged. v3: Minor changes,
accepted by JCA
- …