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Sub-GeV dark matter and multidecay signatures from dark showers at beam-dump experiments

Elias Bernreuther1,*, Nicoline Hemme2,†, Felix Kahlhoefer3,‡, Suchita Kulkarni4,§, and Maksym Ovchynnikov5,∥

  • *Contact author: ebernreuther@ucsd.edu
  • †Contact author: nicoline.hemme@kit.edu
  • ‡Contact author: kahlhoefer@kit.edu
  • §Contact author: suchita.kulkarni@uni-graz.at
  • ∥Contact author: maksym.ovchynnikov@cern.ch
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Phys. Rev. D 113, 075002 – Published 1 April, 2026

DOI: https://doi.org/10.1103/bs36-hvyd

Abstract

In models of strongly interacting dark sectors, the production of dark quarks at accelerators can give rise to dark showers with multiple dark mesons in the final state. If some of these dark mesons are sufficiently light and long-lived, they can be detected with searches for displaced vertices at beam-dump experiments and electron-positron colliders. In this work we focus on the case that dark quark production proceeds via effective operators, while the dark sector analog of the ρ0 meson can decay via kinetic mixing. We evaluate current constraints from NA62 and BABAR as well as sensitivity projections for SHiP and Belle II. We find that there exists a sizeable parameter region where SHiP may detect several displaced vertices in a single event and thus obtain valuable information about the structure of the dark sector.

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Phys. Rev. D 113, 075002– Published 1 April, 2026
  • Received 25 November 2025
  • Accepted 6 February 2026
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