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

TL;DR

This paper explores how dark showers from strongly-interacting dark sectors can produce detectable signals at beam-dump experiments, focusing on sub-GeV dark matter and multi-decay signatures, and evaluates current constraints and future sensitivities.

Contribution

It introduces a model where dark quark production via effective operators leads to observable displaced vertices, providing new insights into dark sector structures at experiments like SHiP and Belle II.

Findings

Sizable parameter space where SHiP can detect multiple displaced vertices

Current constraints from NA62 and BaBar limit dark sector models

Future experiments can significantly improve detection prospects

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 analogue of the $\rho^0$ 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 sizable 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.