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

## TL;DR

This paper explores a strongly interacting dark sector coupled via a vector mediator, analyzing its early universe cosmology and potential signals at the LHC, including dark showers and semi-visible jets.

## Contribution

It introduces a consistent model of a strongly interacting dark sector with a vector mediator, detailing cosmological viability, dark matter freeze-out, and collider signatures.

## Key findings

- Dark vector meson annihilations dominate dark matter freeze-out.
- Existing LHC searches constrain the model despite not being optimized for dark showers.
- Dedicated analyses could improve sensitivity to semi-visible jets.

## 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.