Speaker
Description
In this talk I will go over a new mechanism for setting the relic abundance of a thermal dark matter candidate. Unlike the usual WIMP paradigm, the abundance is set without chemical equilibrium between the Standard Model and the dark sector at freeze-out. The premise is to consider multiple degenerate particles in the dark sector, with a subset of those particles decaying to the visible sector. These “co-decays” set the relic density of the stable particles, which is determined by the usual thermally-averaged cross section but with an additional ingredient: the decay rate. Interestingly, the density of the dark matter candidate is no longer Boltzmann suppressed but has a novel scaling. Such scenarios can be realized in realistic models with broken symmetries. To demonstrate this I will present a plausible model for the dark sector.