Characterising dark matter searches at colliders and direct detection experiments: Vector mediators

TL;DR

This paper introduces a simplified dark matter model framework to compare collider and direct detection experiments, revealing their complementarity and limitations, especially when using effective field theory approximations.

Contribution

The paper develops a Minimal Simplified Dark Matter framework that systematically compares collider and direct detection sensitivities, highlighting the limitations of EFT approaches.

Findings

LHC mono-jet searches outperform direct detection for light DM with vector mediators.

LHC and direct detection experiments probe different parameter space regions for axial-vector mediators.

The complementarity between collider and direct detection searches remains robust in the simplified model framework.

Abstract

We introduce a Minimal Simplified Dark Matter (MSDM) framework to quantitatively characterise dark matter (DM) searches at the LHC. We study two MSDM models where the DM is a Dirac fermion which interacts with a vector and axial-vector mediator. The models are characterised by four parameters: the DM and mediator masses, and the mediator couplings to DM and quarks. The MSDM models accurately capture the full event kinematics, and the dependence on all masses and couplings can be systematically studied. The interpretation of mono-jet searches in this framework can be used to establish an equal-footing comparison with direct detection experiments. For theories with a vector mediator, LHC mono-jet searches possess better sensitivity than direct detection searches for light DM masses (less than 5 GeV). For axial-vector mediators, LHC and direct detection searches generally probe orthogonal directions in the parameter space. We explore the projected limits of these searches from the ultimate reach of the LHC and multi-ton xenon direct detection experiments, and find that the complementarity of the searches remains. Finally, we provide a comparison of limits in the MSDM and effective field theory (EFT) frameworks to highlight the deficiencies of the EFT framework, particularly when exploring the complementarity of mono-jet and direct detection searches.