Dark matter freeze-in from semi-production

Abstract

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 two-component dark matter model and its associated gravitational waves

“…Appropriately assigning U(1) Lµ−Lτ charges for the DM particles, we also address a novel production mechanism, namely the freeze-in mechanism by semi-production processes [83,84] like φ 1 φ 2 ↔ φ 2 φ 2 , that is the inverse of the semi-annihilation process [85]. This mechanism produces an exponentially increasing DM yield, and it typically requires a larger coupling than the standard freeze-in scenarios do, since the DM abundance is also suppressed by the small initial abundance which is generically required for the freeze-in production mechanism.…”

Freeze-in, glaciation, and UV sensitivity from light mediators

“…There is a substantial body of literature studying the interplay between freeze-in and freeze-out processes in determining the final relic abundance of DM in hidden sectors with light mediators [59][60][61][62][63][64][65][66][67][68]. These studies consider the case where the energy density in the dark radiation bath is built up entirely from the energy injected from the SM.…”

Fermion singlet dark matter in a pseudoscalar dark matter portal

“…It is worth to mention that even when the first case with one DM candidate via freeze-in is a perfectly viable DM model, it presents a challenge phenomenology [48] (see however [49]). Recently, novel scenarios with inverse semi-production have been proposed with interesting dark matter production and phenomenology [50,51].…”