Constraining Dark Sectors with Monojets and Dijets

TL;DR

This paper explores how LHC monojet and dijet searches, combined with other constraints, effectively limit dark sector particles interacting via a new mediator, impacting dark matter models and interpretations.

Contribution

It demonstrates the complementarity of monojet and dijet searches in constraining dark sector particles with a new mediator, including broad resonance effects and subcomponent dark matter.

Findings

LHC searches significantly constrain dark sector models with a new mediator.

Dijet resonance bounds complement monojet searches in probing dark sector interactions.

Implications for simplified dark matter models at the LHC are discussed.

Abstract

We consider dark sector particles (DSPs) that obtain sizeable interactions with Standard Model fermions from a new mediator. While these particles can avoid observation in direct detection experiments, they are strongly constrained by LHC measurements. We demonstrate that there is an important complementarity between searches for DSP production and searches for the mediator itself, in particular bounds on (broad) dijet resonances. This observation is crucial not only in the case where the DSP is all of the dark matter but whenever - precisely due to its sizeable interactions with the visible sector - the DSP annihilates away so efficiently that it only forms a dark matter subcomponent. To highlight the different roles of DSP direct detection and LHC monojet and dijet searches, as well as perturbativity constraints, we first analyse the exemplary case of an axial-vector mediator and then generalise our results. We find important implications for the interpretation of LHC dark matter searches in terms of simplified models.