GeV-scale thermal WIMPs: Not even slightly ruled out

Abstract

Weakly interacting massive particles (WIMPs) have long reigned as one of the leading classes of dark matter candidates. The observed dark matter abundance can be naturally obtained by freezeout of weakscale dark matter annihilations in the early Universe. This "thermal WIMP" scenario makes direct predictions for the total annihilation cross section that can be tested in present-day experiments. While the dark matter mass constraint can be as high as m χ ≳ 100 GeV for particular annihilation channels, the constraint on the total cross section has not been determined. We construct the first model-independent limit on the WIMP total annihilation cross section, showing that allowed combinations of the annihilationchannel branching ratios considerably weaken the sensitivity. For thermal WIMPs with s-wave 2 → 2 annihilation to visible final states, we find the dark matter mass is only known to be m χ ≳ 20 GeV. This is the strongest largely model-independent lower limit on the mass of thermal-relic WIMPs; together with the upper limit on the mass from the unitarity bound (m χ ≲ 100 TeV), it defines what we call the "WIMP window." To probe the remaining mass range, we outline ways forward.

Dark matter meets quantum gravity

“…[85]. Since the annihilation process through the vector mediator is an s-wave process, severe bounds from the CMB rule out DM masses below O(10) GeV [86] and a combined analysis of indirect detection experiments leads to O(20) GeV [87].…”

Fat brane, dark matter and localized kinetic terms in six dimensions

“…where m f is the mass of the final states. The (dominant) pwave DM annihilation is therefore not constrained by current observations [109,111]. The observed value of the DM relic density is obtained then through [110] Ω h 2 x f 1.07 × 10 9 GeV −1 g where M Pl is the Planck mass and x f ≡ m DM /T f is the usual ratio between the DM mass and the temperature at the freezeout, which can be taken to be x f = 20.…”

Dark matter capture in celestial objects: improved treatment of multiple scattering and updated constraints from white dwarfs

“…For even lighter dark matter masses, in the MeV range, electron recoil experiments can be more relevant but their sensitivity is also rather modest [15][16][17][18][19]. Interestingly, for indirect detection even in the canonical tens-of-GeV range, the perceived stringent constraints are only for annihilations to specific channels and the less model-dependent constraints are not very stringent [20]. Obviously, the annihilations to neutrinos are much harder to probe.…”