From Kination to Detection: Scotogenic Scalar Dark Matter

Abstract

We investigate scalar dark matter in the scotogenic model during an early kination-dominated epoch. The enhanced expansion rate causes earlier freeze-out and increases the relic abundance, opening viable dark matter masses from approximately $200~\mathrm{GeV}$ to $1~\mathrm{TeV}$ while reducing the need for co-annihilation with a nearly degenerate singlet fermion. Current indirect searches strongly constrain the $(100-200)~\mathrm{GeV}$ region, whereas much of the surviving parameter space can be probed by CTA and next-generation direct detection experiments. The viable spectra also lead to complementary collider signatures, including missing transverse energy, displaced leptons, and disappearing charged tracks, providing promising tests at the HL-LHC and future lepton colliders.