# Cosmic-Ray Signatures of Annihilating and Semi-Annihilating Dark Matter via One-Step Cascades

- Institution: CERN
- Speaker: Tommaso Sassi
- Year: 2026
- Language: English
- Source: [CERN](https://videos.cern.ch/record/3026501)
- Licence: [CERN](https://copyright.web.cern)
- Who can watch: Teens profiles and older (sources give no ratings; placed by Invisible Network from the source's own words)

In this talk I will present a framework in which three classes of dark matter (DM) number-changing processes can affect both the relic abundance via thermal freeze-out and the generation of indirect cosmic-ray (CR) signals today. Namely, I will consider: direct annihilations into Standard Model final states; annihilations into metastable on-shell mediators that later decay into Standard Model particles; semi-annihilations featuring a DM particle in the final state, along with a metastable mediator. I will present a spectral template study of CR (γ rays, neutrinos, and antimatter) injection spectra - prior to propagation - comparing the yield of the different collision processes, systematically including semi-annihilations alongside the more common channels, for a variety of benchmark mediator couplings (decay modes). Through a largely model-independent approach, I will also discuss the extension to scenarios where multiple processes coexist, and discuss how their interplay shapes indirect detection signatures upon varying the relative importance of the three processes. Each scenario can be linked to specific physical realizations that are discussed. As an application, I will discuss the observable γ-ray fluxes from dwarf spheroidal galaxies in the GeV-TeV window. This work provides a consistent connection between early-universe dynamics and present-day observables, revealing distinctive features that arise when multiple dark matter processes contribute simultaneously.

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## Lectures

1. [Cosmic-Ray Signatures of Annihilating and Semi-Annihilating Dark Matter via One-Step Cascades](https://invisiblenetwork.ai/learn/cern/3026501/62223d1e253d), 10 min (CERN's player)