[Paper Review] Extended Dark Matter EFT

Tommi Alanne, Florian Goertz|arXiv (Cornell University)|Dec 20, 2017

Particle physics theoretical and experimental studies3 citations

TL;DR

This paper introduces an Extended Dark Matter Effective Field Theory (eDMeFT) framework that includes both dark matter (DM) and a mediator as dynamical fields, enabling consistent descriptions of DM phenomenology across direct detection, relic density, and collider searches. By incorporating dimension-five operators, the framework captures key physics at high energies while preserving gauge symmetry and correlations, revealing strong synergies between mono-jet, Higgs + missing energy, and direct detection constraints—especially for fermionic and scalar DM with (pseudo)scalar mediators.

ABSTRACT

Conventional approaches to describe dark matter phenomenology at collider and (in)direct detection experiments in the form of dark matter effective field theory or simplified models suffer in general from drawbacks regarding validity at high energies and/or generality, limiting their applicability. In order to avoid these shortcomings, we propose a hybrid framework in the form of an effective theory, including, however, both the dark matter states and a mediator connecting the former to the Standard Model fields. Since the mediation can be realized through rather light new dynamical fields allowing for non-negligible collider signals in missing energy searches, the framework remains valid for the phenomenologically interesting parameter region, while retaining correlations dictated by gauge symmetry. Moreover, a richer new-physics sector can be consistently included via higher-dimensional operators. Interestingly, for fermionic and scalar dark matter with a (pseudo-)scalar mediator, the leading effects originate from dimension-five operators, allowing to capture them with a rather small set of new couplings. We finally examine the correlations between constraints from reproducing the correct relic density, direct-detection experiments, and mono-jet and Higgs+missing energy signatures at the LHC.

Motivation & Objective

• To overcome limitations of conventional EFT and simplified models in describing dark matter phenomenology across diverse energy scales.
• To develop a model-independent yet valid framework for high-energy collider searches and low-energy direct detection experiments.
• To systematically include higher-dimensional operators to capture non-minimal dark sector physics beyond the minimal DM-mediator model.
• To explore correlations between relic density, direct detection, and LHC mono-jet/Higgs + missing energy signatures in a consistent, gauge-invariant setup.

Proposed method

• Formalism combines the Standard Model with a singlet DM particle and a (pseudo)scalar mediator as dynamical degrees of freedom.
• Effective Lagrangian includes D=4 and D=5 operators, with couplings such as $ y_S \bar{\chi}_L \chi_R \mathcal{S} $, $ \lambda_{HS} |H|^2 \mathcal{S} $, and $ \frac{\mathcal{S}}{\Lambda} c_{\text{int}} \mathcal{O} $ for higher-dimensional interactions.
• The framework maintains gauge invariance and validity at TeV-scale collider energies by keeping the mediator as a physical state.
• Phenomenological constraints are derived from direct detection (nuclear recoil), relic density (freeze-out), and LHC signatures (mono-jet, Higgs + missing energy).
• Resonance searches for the mediator in di-jet, $ t\bar{t} $, and di-boson final states are consistently described via s-channel exchange.
• The approach allows for systematic exploration of correlations between observables, such as invisible Higgs decays and DM production via $ D=5 $ operators.

Experimental results

Research questions

• RQ1 How can a unified effective field theory describe dark matter phenomenology across direct detection, relic density, and collider experiments without losing validity or generality?
• RQ2 What are the dominant contributions to DM interactions when both the DM and a (pseudo)scalar mediator are included as dynamical fields?
• RQ3 How do dimension-five operators in the eDMeFT framework affect LHC signatures such as mono-jet and Higgs + missing energy processes?
• RQ4 What are the key correlations between invisible Higgs decays, direct detection limits, and collider constraints in this framework?
• RQ5 In what parameter regions is the mediator detectable via resonant production in di-jet or $ t\bar{t} $ final states?

Key findings

• For fermionic and scalar DM with a (pseudo)scalar mediator, leading effects arise from dimension-five operators, significantly reducing the number of required new couplings.
• Gluon-induced production of the mediator leads to sizable LHC cross sections for both fermionic and scalar DM, making it a promising channel for collider searches.
• Pseudoscalar mediators remain weakly constrained by direct detection, making future direct detection experiments crucial for probing this regime.
• Invisible Higgs decays strongly constrain $ D=4 $ portal couplings like $ \lambda_{HS}^\prime $, but $ D=5 $ operators can evade these bounds by avoiding direct Higgs-DM coupling.
• Resonant production of the mediator in di-jet and $ t\bar{t} $ final states provides a complementary probe of the mediator's couplings, especially when combined with other observables.
• The eDMeFT framework reveals strong correlations between relic density, direct detection, and collider signatures, enabling a unified interpretation of multi-messenger DM constraints.