Among the production mechanisms for dark matter, freeze-in can be a viable channel for very weakly-coupled particles, which can be looked for in terrestrial experiments. This scenario has been recently challenged with respect to the nature of the curvature perturbations that it would generate on large scales. I will argue that these perturbations are adiabatic in nature, avoiding the stringent constraints on isocurvature perturbations, and that freeze-in is thus a viable production mechanism.
Florian Herren