The case for co-decaying dark matter December 5, 2016 by Lisa Zyga feature Please Register or Log in to view the hidden image! A timeline of co-decaying dark matter: the standard model and dark sector decouple at Td, the dark sector density begins to decrease at TΓ, and dark matter “freezes out” at Tf, resulting in a relic abundance. Credit: Dror et al. ©2016 American Physical Society (Phys.org)—There isn't as much dark matter around today as there used to be. According to one of the most popular models of dark matter, the universe contained much more dark matter early on when the temperature was hotter. As the universe cooled, the dark matter annihilated away, at least up until a point when thermal equilibrium was reached and the annihilations ceased, resulting in the number of dark matter particles in the universe "freezing out" and remaining roughly constant. Read more at: http://phys.org/news/2016-12-case-co-decaying-dark.html#jCp
https://arxiv.org/pdf/1607.03110v1.pdf Co-Decaying Dark Matter We propose a new mechanism for thermal dark matter freezeout, termed Co-Decaying Dark Matter. Multi-component dark sectors with degenerate particles and out-of-equilibrium decays can co-decay to obtain the observed relic density. The dark matter density is exponentially depleted through the decay of nearly degenerate particles, rather than from Boltzmann suppression. The relic abundance is set by the dark matter annihilation cross-section, which is predicted to be boosted, and the decay rate of the dark sector particles. The mechanism is viable in a broad range of dark matter parameter space, with a robust prediction of an enhanced indirect detection signal. Finally, we present a simple model that realizes co-decaying dark matter.
