Thermal WIMPs and the Scale of New Physics: Global Fits of Dirac Dark Matter Effective Field Theories

TL;DR

This study uses a comprehensive global fit to analyze Dirac fermion WIMP dark matter models with effective operators, assessing their viability against latest experimental data and EFT validity constraints.

Contribution

It provides the first detailed global analysis of Dirac WIMP EFTs including multiple operators, experimental data, and EFT validity considerations.

Findings

EFT validity is challenged for DM masses below 100 GeV at LHC energies.

Viable parameter space exists where WIMPs can account for dark matter and satisfy all constraints.

Results are sensitive to the choice of EFT validity prescription and LHC data excesses.

Abstract

We assess the status of a wide class of WIMP dark matter (DM) models in light of the latest experimental results using the global fitting framework $\textsf{GAMBIT}$. We perform a global analysis of effective field theory (EFT) operators describing the interactions between a gauge-singlet Dirac fermion and the Standard Model quarks, the gluons and the photon. In this bottom-up approach, we simultaneously vary the coefficients of 14 such operators up to dimension 7, along with the DM mass, the scale of new physics and several nuisance parameters. Our likelihood functions include the latest data from $\mathit{Planck}$, direct and indirect detection experiments, and the LHC. For DM masses below 100 GeV, we find that it is impossible to satisfy all constraints simultaneously while maintaining EFT validity at LHC energies. For new physics scales around 1 TeV, our results are influenced by several small excesses in the LHC data and depend on the prescription that we adopt to ensure EFT validity. Furthermore, we find large regions of viable parameter space where the EFT is valid and the relic density can be reproduced, implying that WIMPs can still account for the DM of the universe while being consistent with the latest data.