Toward a Comprehensive Exploration of Flavored Dark Matter Models

TL;DR

The paper develops a comprehensive, publicly available toolchain for exploring flavored dark matter (DM) models by unifying relic-density calculations, direct and indirect detection, collider constraints, and a global flavor analysis via SMEFT matching with RG evolution. It applies the framework to two Majorana DM scenarios—coupled to right-handed leptons and to right-handed down-type quarks—using DMFV flavor structure and canonical thermal freeze-out, and finds that relic density and flavor observables (notably $\mu \to e \gamma$ and $\varepsilon_K$) strongly constrain the parameter space. Leptophilic setups retain sizable viable regions, with LHC bounds mostly affecting low-mass corners, while quark-coupling scenarios face much tighter restrictions from direct detection and meson mixing, with bottom-philic textures offering more room for new physics. The study demonstrates the dominance of hierarchical flavor structures in evading flavor-changing limits and highlights the need for targeted collider and flavor searches to cover remaining viable regions; the framework enables rapid extension to the full 20-model landscape and other UV completions. The results have practical impact by guiding model-building toward naturally hierarchical couplings and by providing a robust pipeline for confronting flavored DM with current and future experimental data, all via a reproducible, open-source platform. The key methodological novelty lies in integrating one-loop SMEFT matching (via Matchete) with RG evolution (SMEFT and LEFT) and a global flavor likelihood (smelli/flavio) within a single pipeline that interfaces with collider, direct Detection, and relic-density tools. $\Omega h^2 = 0.120 \pm 0.001$ serves as the relic-density anchor, while flavor observables translate UV couplings into low-energy constraints across the parameter space.$

Abstract

We present a comprehensive framework for the study of flavored dark matter models, combining relic density calculations with direct and indirect detection limits, collider constraints, and a global analysis of flavor observables based on SMEFT matching and renormalization-group evolution. The framework applies to scalar or fermionic dark matter, including both self-conjugate and non-self-conjugate cases. As a proof of principle, we analyze two scenarios with Majorana dark matter coupling to right-handed charged leptons and to right-handed down-type quarks, assuming a thermal freeze-out. In the leptophilic case, flavor-violating decays such as $μ\to e γ$ dominate the constraints, while LHC searches still leave sizable parameter space. For quark couplings, direct detection bounds and meson mixing severely restrict the allowed couplings, favoring hierarchical flavor structures. The toolchain presented in this paper is publicly available on GitHub (https://github.com/lena-ra/Flavored-Dark-Matter).

Figures (8)

• Figure 1: Schematic visualization of the interaction of a DM field $X$ with a SM fermion $f$ and a mediator field $Y$. Here $i,j$ are (SM and dark) flavor indices.
• Figure 2: Illustration of the numerical toolchain used in our analysis of flavored DM models. The gray rounded rectangles show the inputs to the toolchain (i.e. the Lagrangian of the DM model and the values for all parameters) and light purple boxes show the tools used.
• Figure 3: Constraints on the parameter space for the Majorana DM model coupling to right-handed leptons. Points shown by orange square markers are excluded by flavor observables while still passing the LHC and relic abundance constraints. Blue square markers fulfill only the relic abundance constraints but are excluded by constraints from the LHC. The remaining points that pass all constraints are shown with green circles. The upper left panel shows the parameter space in the $M_{\tilde{\chi}_1}$–$M_\varphi$ plane, with the gray dashed line indicating $M_{\tilde{\chi}_1} = M_\varphi$. The upper right panel displays the mass splitting parameter $\eta$ versus $M_{\tilde{\chi}_1}$. The lower panels show the sum over all DM states of $\tilde{\lambda}_{\mu i} \tilde{\lambda}^*_{e i}$ on the left and $\tilde{\lambda}_{\tau i} \tilde{\lambda}^*_{e i}$ on the right versus $M_\varphi$.
• Figure 4: Feynman diagrams contributing to meson--anti-meson mixing in quarkphilic Majorana DM models. While the diagram on the left-hand side is present also in Dirac models, the diagram on the right-hand side only contributes in the Majoran scenario.
• Figure 5: Constraints on $\sqrt{D_1^2 + D_2^2 + D_3^2}$ and $M_\varphi/M_{\tilde{\chi}_1} - 1$ for the Majorana DM model coupling to right-handed down-type quarks where the left panel shows the results for the general hierarchical scenario and the right panel shows the ones for bottom-philic scenario. The color-code is the same as in Fig. \ref{['fig:allowed_leptons']} with the addition of direct detection constraints in red. The dashed gray lines in the left panel depict the region excluded in the general hierarchical scan by requiring either $\sqrt{D_1^2 + D_2^2 + D_3^2} > 0.6$ or $M_\varphi/M_{\tilde{\chi}_1} - 1 < 0.1$.