Large Neutrino-Dark Matter Interactions: From Effective Field Theory to Ultraviolet Completions

TL;DR

The paper develops a general EFT framework for neutrino–DM interactions by constructing DM-LEFT and DM-SMEFT operator bases and systematically deriving all gauge-invariant UV completions at operator dimensions 6–8. It then builds minimal UV-complete models across Majorana, Dirac, scalar, and vector DM, including a scotogenic inert-doublet realization that yields large neutrino–DM couplings while respecting neutrino mass and charged-lepton constraints. Phenomenological analyses cover DM relic abundance, direct detection, and cosmological and laboratory constraints, demonstrating that effective neutrino–DM couplings can exceed the Fermi scale by several orders of magnitude in viable regions, e.g., up to ∼10^5 G_F in some Type-II seesaw-inspired setups. The work provides a concrete EFT-to-UV roadmap linking low-energy neutrino–DM scattering to UV mediator content, with multiple testable predictions for future collider, cosmology, and direct-detection experiments.

Abstract

We develop a general effective field theory (EFT) framework for neutrino-dark matter (DM) interactions, and apply it to systematically find all possible gauge-invariant ultraviolet (UV) completions at a given EFT operator dimension. Our goal here is to find simple UV-complete models that can realize potentially large neutrino-DM interactions, while being consistent with all existing theoretical and experimental constraints. We first construct the leading non-derivative operator basis for neutrino-DM scattering in a low-energy effective theory with neutrinos and DM (DM-LEFT), together with its gauge-invariant embedding in the Standard Model EFT (DM-SMEFT). We then construct all renormalizable tree-level UV completions that generate the relevant DM-SMEFT operators up to dimension-8 using a topology-based classification. Using this framework, we present minimal UV-complete models for different DM types that can yield effective neutrino-DM couplings up to several orders of magnitude larger than the Fermi coupling, while satisfying all constraints, most notably from neutrino mass and from the charged-lepton sector. This includes a pseudo-Dirac fermion DM realization in the scotogenic neutrino mass model and models of Majorana DM inspired by type-II and inverse seesaw-based neutrino mass models. Phenomenological implications for DM thermal relic abundance and direct detection prospects, as well as various cosmological and laboratory constraints on the model parameter space, are also analyzed.

Figures (7)

• Figure 1: Tree-level renormalizable diagram topologies used to construct UV completions of the DM-SMEFT operators in Table \ref{['tab:operators']} at $d=6$, 7 and 8. External legs (black) represent the operator fields ($L$, $H$, and the dark-sector fields), while internal lines (red) denote heavy mediators. Solid (dashed) lines correspond to fermions (bosons).
• Figure 2: Feynman diagrams illustrating the UV completions of effective operators arising in Model 1 of Section \ref{['sec:model1']}, which introduces an additional Higgs doublet $\phi_3 \equiv H_2$. (a), and (b) respectively represent the UV completion of ${\cal \widetilde{O}}_{6,M}^3 \equiv (\bar{L}\gamma_\mu L)(\bar{\chi_L}\gamma^\mu\chi_L)$ and ${\cal \widetilde{O}}_{8,M}^1 \equiv (\vec{L}\!\cdot\!\vec{H}\,\vec{L}\!\cdot\!\vec{H})(\chi_L\chi_L)$.
• Figure 3: One-loop neutrino mass in the scotogenic model through the effective dimension-5 operator $LLHH$.
• Figure 4: Summary of Model 1 prediction in the mediator mass $m_{\rm med} \equiv m_{H_2^0}$ versus Yukawa coupling $y_\chi^{i3}$ plane for a benchmark mass ratio $m_\chi = m_{\rm med}/3$. The shaded regions are excluded by BBN (purple), $K$ (blue) and $D$ (red) meson decays, $Z$ invisible decay (gray) and DM direct detection (orange) constraints. The dark green curve indicates the coupling values required for the thermal DM freeze-out into neutrinos that reproduces the observed relic abundance.
• Figure 5: Feynman diagrams illustrating the UV completions of effective operators ${\widetilde{\cal O}}_{8,M}^1 \equiv (\vec{L}\cdot \vec{H}\ \vec{L}\cdot \vec{H}) \chi_L \chi_L$ and ${\widetilde{\cal O}}_{8,M}^2 \equiv (\vec{L}\cdot \vec{H}\ \vec{L}\cdot \vec{H}) \chi^c_{~R} \chi^c_{~R}$ arising in Model 2, which introduces an additional singlet scalar $S$ and a triplet scalar $\Delta$.