Making dark matter out of light: Freeze-in from plasma effects

摘要: Dark matter (DM) could couple to particles in the Standard Model (SM) through a light vector mediator. In limit of small coupling, this portal be responsible for producing observed DM abundance mechanism known as freeze-in. Furthermore, requisite DM-SM couplings provide concrete benchmark direct and indirect searches DM. We present updated calculations relic produced by freeze-in identify an additional production channel: decay photons that acquire in-medium plasma mass. These plasmon decays are dominant channel sub-MeV masses, including leads significant reduction predicted signal strength searches. Accounting from both annihilations SM fermions, acquires highly nonthermal phase-space distribution which impacts cosmology at later times; these cosmological effects will explored companion paper.