A balance for Dark Matter bound states

TL;DR

This paper explores the potential for detecting strongly interacting Dark Matter particles through bound states with ordinary matter, proposing laboratory tests and a detection setup to identify such particles with large cross sections.

Contribution

It introduces the concept of bound states between Dark Matter and ordinary matter as a novel detection method for strongly interacting Dark Matter candidates.

Findings

Bound states with binding energy >1 meV are possible.

Laboratory detection could measure capture cross sections of barn scale.

Cryogenic samples could accumulate Dark Matter, enabling detection.

Abstract

Massive particles with self interactions of the order of 0.2 barn/GeV are intriguing Dark Matter candidates from an astrophysical point of view. Current and past experiments for direct detection of massive Dark Matter particles are focusing to relatively low cross sections with ordinary matter, however they cannot rule out very large cross sections, $\sigma/M > 0.01$ barn/GeV, due to atmosphere and material shielding. Cosmology places a strong indirect limit for the presence of large interactions among Dark Matter and baryons in the Universe, however such a limit cannot rule out the existence of a small sub-dominant component of Dark Matter with non negligible interactions with ordinary matter in our galactic halo. Here, the possibility of the existence of bound states with ordinary matter, for a similar Dark Matter candidate with not negligible interactions, is considered. The existence of bound states, with binding energy larger than $\sim$1 meV, would offer the possibility to test in laboratory capture cross sections of the order of a barn (or larger). The signature of the detection for a mass increasing of cryogenic samples, due to the possible particle accumulation, would allow the investigation of these Dark Matter candidates with mass up to the GUT scale. A proof of concept for a possible detection set-up and the evaluation of some noise sources are described.