Bouncing Dark Matter

Abstract

We present a novel mechanism for thermal dark matter production, characterized by a "bounce": the dark matter equilibrium distribution transitions from the canonical exponentially falling abundance to an exponentially rising one, resulting in an enhancement of the freezeout abundance by several orders of magnitude. We discuss multiple qualitatively different realizations of bouncing dark matter. The bounce allows the present day dark matter annihilation cross section to be significantly larger than the canonical thermal target, improving the prospects for indirect detection signals.

Fermion singlet dark matter in a pseudoscalar dark matter portal

“…5, we have projected the points in different planes, with the color of each point indicating the corresponding value of tan θ. As it is expected in the normal hierarchy m ψ > m χ , the first two plots corroborate the fact that the weighted cross sections never overpass the thermal cross section reference (pink regions) 5 . The other two plots in the right of the first line show the corresponding values for the couplings of the model.…”

“…Although this bouncing effect in the yield of some specie has been already observed in the context of thermal DM, see e.g. [6,7,8], the connection of this yield feature with indirect detection has only been worked in [5].…”

“…In this subsection, we study the values of some of the most relevant average annihilation cross section times relative velocity at v rel → 0 from DM (semi)annihilation, especially when they overpass the thermal canonical value 2 − 3 × 10 −26 cm 3 /s [5]. We run two random scans, one considering m χ = 300 GeV and the other m χ = 700 GeV.…”

“…Recently, it has been suggested that in specific scenarios, the yield of a DM specie in the early universe could have been undergoing a different pattern of decoupling, with a period of exponential growth before completely freeze-out. This idea has been called bouncing dark matter [5]. Although this bouncing effect in the yield of some specie has been already observed in the context of thermal DM, see e.g.…”

An asymmetric SIMP dark matter model

“…may still be subject to the CMB constraint 7. A more detailed discussion of the bouncing effect of DM can be found in recent paper[32] 8. The conjugate 3 → 2 process X X X → NN with the same reaction rate as XXX → N N can also produce the N after the chemical freeze-out of DM.…”