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We consider dark matter (DM) with very weak couplings to the standard model (SM), such that its self-annihilation cross section is much smaller than the canonical one, $langlesigma vrangle_{chichi} ll 10^{-26}mathrm{cm}^3/mathrm{s}$. In this case DM self-annihilation is negligible for the dynamics of freeze-out and DM dilution is solely driven by efficient annihilation of heavier accompanying dark sector particles provided that DM maintains chemical equilibrium with the dark sector. This chemical equilibrium is established by conversion processes which require much smaller couplings to be efficient than annihilation. The chemical decoupling of DM from the SM can either be initiated by the freeze-out of annihilation, resembling a co-annihilation scenario, or of conversion processes, leading to the scenario of conversion-driven freeze-out. We focus on the latter and discuss its distinct phenomenology.
We study the stochastic background of gravitational waves which accompany the sudden freeze-out of dark matter triggered by a cosmological first order phase transition that endows dark matter with mass. We consider models that produce the measured da
Non-thermalized dark matter is a cosmologically valid alternative to the paradigm of weakly interacting massive particles. For dark matter belonging to a $Z_2$-odd sector that contains in addition a thermalized mediator particle, dark matter producti
It is quite conceivable that dark matter freeze-out occurred during an early period of matter domination, in which case the evolution and relic abundance differ from standard freeze-out calculations which assume a radiation dominated universe. Here w
We investigate whether right-handed neutrinos can play the role of the dark matter of the Universe and be generated by the freeze-out production mechanism. In the standard picture, the requirement of a long lifetime of the right-handed neutrinos impl
We propose a novel scenario of Dark Matter production naturally connected with generation of gravitational waves. Dark Matter is modelled as a real scalar, which interacts with the hot primordial plasma through a portal coupling to another scalar fie