Constraining Dark Sectors at Colliders: Beyond the Effective Theory Approach

TL;DR

This paper develops simplified collider models for dark matter searches, incorporating various mediator types and effects, and compares collider constraints with direct and indirect detection methods, providing a comprehensive framework for interpreting experimental results.

Contribution

It introduces a set of benchmark simplified models with detailed mediator interactions, including full top-mass effects and potential new physics contributions, for more accurate dark matter searches at the LHC.

Findings

LHC limits for all four mediator types at 8 and 14 TeV.

Resolved top-quark effects in scalar and pseudo-scalar channels.

Impact of heavy new physics loops on production processes.

Abstract

We outline and investigate a set of benchmark simplified models with the aim of providing a minimal simple framework for an interpretation of the existing and forthcoming searches of dark matter particles at the LHC. The simplified models we consider provide microscopic QFT descriptions of interactions between the Standard Model partons and the dark sector particles mediated by the four basic types of messenger fields: scalar, pseudo-scalar, vector or axial-vector. Our benchmark models are characterised by four to five parameters, including the mediator mass and width, the dark matter mass and an effective coupling(s). In the gluon fusion production channel we resolve the top-quark in the loop and compute full top-mass effects for scalar and pseudo-scalar messengers. We show the LHC limits and reach at 8 and 14 TeV for models with all four messenger types. We also outline the complementarity of direct detection, indirect detection and LHC bounds for dark matter searches. Finally, we investigate the effects which arise from extending the simplified model to include potential new physics contributions in production. Using the scalar mediator as an example we study the impact of heavy new physics loops which interfere with the top mediated loops. Our computations are performed within the MCFM framework and we provide fully flexible public Monte Carlo implementation.