Strongly interacting dark sectors in the early Universe and at the LHC through a simplified portal

Abstract

We study the cosmology and LHC phenomenology of a consistent strongly interacting dark sector coupled to Standard Model particles through a generic vector mediator. We lay out the requirements for the model to be cosmologically viable, identify annihilations into dark vector mesons as the dominant dark matter freeze-out process and discuss bounds from direct detection. At the LHC the model predicts dark showers, which can give rise to semi-visible jets or displaced vertices. Existing searches for di-jet resonances and for missing energy mostly probe the parameter regions where prompt decays are expected and constrain our model despite not being optimised for dark showers. We also estimate the sensitivity of dedicated analyses for semi-visible jets and emphasize the complementarity of different search strategies.