arXiv subjects

Lena Rathmann

Publications and source records attributed to Lena Rathmann.

5 recordsLinked to original sources

arXiv2026

Conversion-Driven Baryogenesis in Flavored Dark Matter Models

The dark matter and baryon asymmetry problems remain two of the most pressing questions in fundamental physics. Considering lepton-flavored dark matter, it has recently been shown that the cogenesis of dark matter and the baryon asymmetry can be economically achieved via conversion-driven freeze-out. This mechanism leverages semi-efficient conversions to drive a departure from equilibrium while preserving independence from initial conditions through early thermalization of the dark sector. In this work, we develop this mechanism further, providing a detailed analysis of the chemical-equilibrium conditions and demonstrating that the framework can be extended to quark-philic scenarios, where the matter-antimatter asymmetry is generated resonantly through baryon-number-conserving $CP$-violating conversions of a mediator field into Standard Model quarks and dark matter. The strong QCD interactions of the colored mediator, including bound-state formation effects during freeze-out, substantially enlarge the viable parameter space and allow dark matter masses from a few hundred GeV up to the TeV scale. We furthermore assess the impact of thermal effects by comparing a minimal treatment with a setup that approximately accounts for thermal masses and their kinematic consequences. The resulting scenario predicts striking long-lived particle signatures with soft displaced decay products that remain only partially explored at the LHC and motivate dedicated searches at the HL-LHC.

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arXiv2025

Toward a Comprehensive Exploration of Flavored Dark Matter Models

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 $\mu \to e \gamma$ 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).

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arXiv2025

t-channel dark matter at the LHC -- a whitepaper

This report, summarising work achieved in the context of the LHC Dark Matter Working Group, investigates the phenomenology of $t$-channel dark matter models, spanning minimal setups with a single dark matter candidate and mediator to more complex constructions closer to UV-complete models. For each considered class of models, we examine collider, cosmological and astrophysical implications. In addition, we explore scenarios with either promptly decaying or long-lived particles, as well as featuring diverse dark matter production mechanisms in the early universe. By providing a unified analysis framework, numerical tools and guidelines, this work aims to support future experimental and theoretical efforts in exploring $t$-channel dark matter models at colliders and in cosmology.

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arXiv2024

$\overline{\text{D}}$arkRayNet: Emulation of cosmic-ray antideuteron fluxes from dark matter

Cosmic-ray antimatter, particularly low-energy antideuterons, serves as a sensitive probe of dark matter annihilating in our Galaxy. We study this smoking-gun signature and explore its complementarity with indirect dark matter searches using cosmic-ray antiprotons. To this end, we develop the neural network emulator $\overline{\text{D}}$arkRayNet, enabling a fast prediction of propagated antideuteron energy spectra for a wide range of annihilation channels and their combinations. We revisit the Monte Carlo simulation of antideuteron coalescence and cosmic-ray propagation, allowing us to explore the uncertainties of both processes. In particular, we take into account uncertainties from the $\Lambda_b$ production rate and consider two distinctly different propagation models. Requiring consistency with cosmic-ray antiproton limits, we find that AMS-02 shows sensitivity to a few windows of dark matter masses only, most prominently below 20 GeV. This region can be probed independently by the upcoming GAPS experiment. The program package $\overline{\text{D}}$arkRayNet is available on GitHub.

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arXiv2023

Flavoured Majorana Dark Matter then and now: From freeze-out scenarios to LHC signatures

We study a simplified Dark Matter model in the Dark Minimal Flavour Violation framework. Our model complements the Standard Model with a flavoured Dark Matter Majorana triplet and a coloured scalar mediator that share a Yukawa coupling with the right-handed up-type quarks with the coupling matrix $\lambda$. We extend previous work on this topic by exploring a large range of cosmologically viable parameter space, including the coannihilation region and, in particular, the region of conversion-driven freeze-out, while considering constraints from $D^0-\bar D^0$ mixing as well as constraints from direct and indirect Dark Matter searches. We find various realisations of conversion-driven freeze-out within the model, that open up allowed windows of parameter space towards small mass splittings and very weak Dark Matter couplings. Finally, we probe the model by reinterpreting current LHC searches for missing energy and long-lived particles. We point out gaps in the coverage of current constraints as well as new opportunities to search for the model at the LHC, in particular, the charge asymmetry in single-top production associated with jets and missing energy.

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