Beyond the Dark matter effective field theory and a simplified model approach at colliders

TL;DR

This paper investigates the limitations of effective field theories and simplified models in collider searches for singlet fermion dark matter with Higgs portal interactions, emphasizing the importance of full gauge invariance and renormalizability.

Contribution

It introduces a renormalizable model with a singlet scalar messenger that respects SM gauge symmetry, providing more accurate collider bounds and interpretations.

Findings

Collider bounds differ significantly from EFT predictions.

Full gauge invariance affects the interpretation of monojet and tar{t} + missing energy data.

Emphasizes the importance of unitarity and renormalizability in dark matter models.

Abstract

Direct detection of and LHC search for the singlet fermion dark matter (SFDM) model with Higgs portal interaction are considered in a renormalizable model where the full Standard Model (SM) gauge symmetry is imposed by introducing a singlet scalar messenger. In this model, direct detection is described by an effective operator m_q \bar{q} q \bar{\chi} \chi as usual, but the full amplitude for monojet + \not E_T involves two intermediate scalar propagators, which cannot be seen within the effective field theory (EFT) or in the simplified model without the full SM gauge symmetry. We derive the collider bounds from the ATLAS monojet + \not E_T as well as the CMS t\bar{t} + \not E_T data, finding out that the bounds and the interpretation of the results are completely different from those obtained within the EFT or simplified models. It is pointed out that it is important to respect unitarity, renormalizability and local gauge invariance of the SM.