A
bstract
We study a novel dark matter production mechanism based on the freeze-in through
semi-production
, i.e. the inverse semi-annihilation processes. A peculiar feature of this scenario is that ...the production rate is suppressed by a small initial abundance of dark matter and consequently creating the observed abundance requires much larger coupling values than for the usual freeze-in. We provide a concrete example model exhibiting such production mechanism and study it in detail, extending the standard formalism to include the evolution of dark matter temperature alongside its number density and discuss the importance of this improved treatment. Finally, we confront the relic density constraint with the limits and prospects for the dark matter indirect detection searches. We show that, even if it was never in full thermal equilibrium in the early Universe, dark matter could, nevertheless, have strong enough present-day annihilation cross section to lead to observable signals.
A
bstract
Theories with more than one scalar field often exhibit phase transitions producing potentially detectable gravitational wave (GW) signal. In this work we study the semi-annihilating
ℤ
3
...dark matter model, whose dark sector comprises an inert doublet and a complex singlet, and assess its prospects in future GW detectors. Without imposing limits from requirement of providing a viable dark matter candidate, i.e. taking into account only other experimental and theoretical constraints, we find that the first order phase transition in this model can be strong enough to lead to a detectable signal. However, direct detection and the dark matter thermal relic density constraint calculated with the state-of-the-art method including the impact of early kinetic decoupling, very strongly limit the parameter space of the model explaining all of dark matter
and
providing observable GW peak amplitude. Extending the analysis to underabundant dark matter thus reveals region with detectable GWs from a single-step or multi-step phase transition.
When building CP-symmetric models beyond the Standard Model, one can impose CP symmetry of higher order. This means that one needs to apply the CP transformation more than two times to get the ...identity transformation, but still the model is perfectly CP-conserving. A multi-Higgs-doublet model based on CP symmetry of order 4, dubbed CP4, was recently proposed and its phenomenology is being explored. Here, we show that the construction does not stop at CP4. We build examples of renormalizable multi-Higgs-doublet potentials which are symmetric under CP8 or CP16, without leading to any accidental symmetry. If the vacuum conserves CP symmetry of order 2k, then the neutral scalars become CP eigenstates, which are characterized not by CP parities but by CP charges defined modulo 2k. One or more lightest states can be the dark matter candidates, which are protected against decay not by the internal symmetry but by the exotic CP. We briefly discuss their mass spectra and interaction patterns for CP8 and CP16.
The DAMPE excess and gamma-ray constraints Belotsky, Konstantin; Kamaletdinov, Airat; Laletin, Maxim ...
PHYSICS OF THE DARK UNIVERSE,
December 2019, 2019-12-00, 2019-12, Volume:
26
Journal Article, Web Resource
Peer reviewed
Open access
The direct measurements of the cosmic electron–positron spectrum around 1 TeV made by DAMPE have induced many theoretical speculations about possible excesses in the data above the standard ...astrophysical predictions that might have the dark matter (DM) origin. These attempts mainly fall into two categories: (i) DM annihilations (or decays) in the Galactic halo producing the broad spectrum excess; (ii) DM annihilations in the nearby compact subhalo producing the sharp peak at 1.4TeV. We investigate the gamma-ray emission accompanying e+e− production in DM annihilations, as well as various theoretical means to suppress the prompt radiation, such as specific interaction vertices or multi-cascade modes, and conclude that these attempts are in tension with various gamma-ray observations. We show that the DM explanations of the broad spectrum excess tend to contradict the diffuse isotropic gamma-ray background (IGRB), measured by Fermi-LAT, while the nearby subhalo scenario is constrained by nonobservation in the surveys, performed by Fermi-LAT, MAGIC and HESS. We also briefly review other types of gamma-ray constraints, which seem to rule out the DM interpretations of the DAMPE broad spectrum excess as well.
Abstract Theories with more than one scalar field often exhibit phase transitions producing potentially detectable gravitational wave (GW) signal. In this work we study the semi-annihilating ℤ 3 dark ...matter model, whose dark sector comprises an inert doublet and a complex singlet, and assess its prospects in future GW detectors. Without imposing limits from requirement of providing a viable dark matter candidate, i.e. taking into account only other experimental and theoretical constraints, we find that the first order phase transition in this model can be strong enough to lead to a detectable signal. However, direct detection and the dark matter thermal relic density constraint calculated with the state-of-the-art method including the impact of early kinetic decoupling, very strongly limit the parameter space of the model explaining all of dark matter and providing observable GW peak amplitude. Extending the analysis to underabundant dark matter thus reveals region with detectable GWs from a single-step or multi-step phase transition.
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