Impact of bound states on non-thermal dark matter production

Abstract

We explore the impact of non-perturbative effects, namely Sommerfeld enhancement and bound state formation, on the cosmological production of non-thermal dark matter. For this purpose, we focus on a class of simplified models with t-channel mediators. These naturally combine the requirements for large corrections in the early Universe, i.e. beyond the Standard Model states with long range interactions, with a sizable new physics production cross section at the LHC. We find that the dark matter yield of the superWIMP mechanism is suppressed considerably due to the non-perturbative effects under consideration. This leads to a significant shift in the cosmologically preferred parameter space of non-thermal dark matter in these models. We also revisit the implications of LHC bounds on long-lived particles associated with non-thermal dark matter and find that testing this scenario at the LHC is a bigger challenge than previously anticipated.

Strong electroweak phase transition in t-channel simplified dark matter models

“…ref. [105] for the same model). We fixed the dark matter mass to M χ = 300 GeV, considered three relative mass splittings ∆M/M χ ∈ {0.1, 0.05, 0.01}, and fixed the Higgs-portal coupling to λ 3 = 2.5.…”

“…We also include the Higgs-portal coupling contribution to the scalar mediator annihilations, that are often neglected for the model at hand (an exception is ref. [105]). We include them in the numerical extraction of the energy density, and list the expression of the corresponding cross sections in the appendix B.…”

“…Then, for the Z-boson induced bound states, we obtain a lower bound M η 70 TeV, which is higher than the masses we are interested in (our estimate compares well with the one detailed recently in ref. [105]). For the Higgs boson, we find that even for the largest coupling that we allowed, λ 3 = 3.0, the bound gives M η 5 TeV.…”

“…For recent investigations of freeze-in production, super-WIMP, and conversion-driven freeze-out of the model considered in our work, see refs. [94,105]. There the above-mentioned effects have not been included.…”

Impact of Sommerfeld effect and bound state formation in simplified t-channel dark matter models

“…• While recently the effects of BSF on the relic density have been considered in the context of the conversion-driven freeze-out [38] and the superWIMP mechanism [39], we investigate in this article, the scenario where DM is in thermal equilibrium with the dark sector and the SM.…”