Observational Properties of Feebly Coupled Dark Matter

Abstract

We show that decoupled hidden sectors can have observational consequences. As a representative model example, we study dark matter production in the Higgs portal model with one real singlet scalar s coupled to the Standard Model Higgs via λhsΦ†Φs 2 and demonstrate how the combination of non-observation of cosmological isocurvature perturbations and astrophysical limits on dark matter self-interactions imply stringent bounds on the magnitude of the scalar self-coupling λss 4 . For example, for dark matter mass ms = 10 MeV and Hubble scale during cosmic inflation H∗ = 1012 GeV, we find 10−4 . λs . 0.2.