[Paper Review] The Higgs-portal for Dark Matter:effective field theories versus concrete realizations

Giorgio Arcadi, A. Djouadi+1 more|arXiv (Cornell University)|Jan 7, 2021

Dark Matter and Cosmic PhenomenaPhysics and Astronomy92 references39 citations

TL;DR

This paper evaluates the validity of effective Higgs-portal models for dark matter (DM) by comparing them to UV-complete realizations across scalar, fermionic, and vector DM scenarios. It finds that the effective field theory (EFT) approach remains robust and consistent—especially for invisible Higgs decay searches at the LHC—provided additional scalar states are heavy; however, relic density constraints limit its applicability in narrow regions unless non-thermal mechanisms are invoked.

ABSTRACT

Higgs-portal effective field theories are widely used as benchmarks in order to interpret collider and astroparticle searches for dark matter (DM) particles. To assess the validity of these effective models, it is important to confront them to concrete realizations that are complete in the ultraviolet regime. In this paper, we compare effective Higgs-portal models with scalar, fermionic and vector DM with a series of increasingly complex realistic models, taking into account all existing constraints from collider and astroparticle physics. These complete realizations include the inert doublet with scalar DM, the singlet-doublet model for fermionic DM and models based on spontaneously broken dark SU(2) and SU(3) gauge symmetries for vector boson DM. We also discuss the simpler scenarios in which a new scalar singlet field that mixes with the standard Higgs field is introduced with minimal couplings to isosinglet spin--$0, \frac12$ and 1 DM states. We show that in large regions of the parameter space of these models, the effective Higgs-portal approach provides a consistent limit and thus, can be safely adopted, in particular for the interpretation of searches for invisible Higgs boson decays at the LHC. The phenomenological implications of assuming or not that the DM states generate the correct cosmological relic density are also discussed.

Motivation & Objective

• To assess the validity of effective Higgs-portal models for dark matter in light of UV-completed theories.
• To investigate whether EFT predictions remain consistent when confronted with realistic, renormalizable UV completions of scalar, fermionic, and vector DM.
• To determine under what conditions the effective theory can accurately describe DM phenomenology, especially regarding invisible Higgs decays and relic density.
• To explore whether the observed cosmological DM relic density can be naturally achieved in UV-complete models without relying on light scalar mediators.

Proposed method

• Compares effective Higgs-portal models (scalar, fermionic, vector DM) to UV-complete realizations: inert Higgs doublet (scalar), singlet-doublet model (fermionic), and dark U(1), SU(2), SU(3) gauge models (vector DM).
• Analyzes constraints from LHC invisible Higgs decay searches, direct detection (XENON1T, XENONnT, DARWIN), and relic density measurements (Planck).
• Uses perturbative unitarity and renormalizability as criteria to assess theoretical consistency of EFTs.
• Performs parameter space scans across models, evaluating whether EFT predictions match those of UV-completed theories.
• Examines the role of additional scalar states (e.g., mixing with SM Higgs) in spoiling EFT validity when light.
• Evaluates the impact of DM component mixing (e.g., vector + metastable Ψ) on collider and direct detection observables.

Experimental results

Research questions

• RQ1 Under what conditions does the effective Higgs-portal model remain a valid approximation for UV-complete DM theories?
• RQ2 Can the observed cosmological relic density be achieved in UV-completed models without requiring a light scalar mediator?
• RQ3 How do the phenomenological predictions of EFTs compare to those of UV-completed models in invisible Higgs decay and direct detection?
• RQ4 What is the role of additional vector or scalar states in spoiling the EFT limit, and when can they be safely neglected?
• RQ5 In models with multiple DM components (e.g., SU(3) dark sector), can the EFT description still capture the dominant collider phenomenology?

Key findings

• The effective Higgs-portal approach provides a consistent limit across scalar, fermionic, and vector DM models when additional scalar states are heavy (in the TeV range), validating its use for LHC invisible Higgs searches.
• For vector DM, the SU(3) dark gauge group model allows for a stable vector DM plus a lighter metastable Ψ state, enabling correct relic density without light scalars.
• In the SU(3) model, the DM and Ψ states are close in mass, so they are treated as a single effective state in collider searches, preserving EFT consistency.
• The scalar Higgs portal fails as a viable EFT limit due to cancellation mechanisms in the DM-nucleon scattering cross section.
• In the fermionic and vector DM cases, EFT validity breaks down only when additional scalar mediators are light, which is excluded by unitarity and experimental constraints.
• The effective theory remains robust for direct detection and invisible Higgs decay correlations, except in narrow regions like the Higgs pole or light DM, where relic density constraints require non-thermal DM production or light scalars.