New Experimental Constraints in a New Landscape for Composite Dark Matter

TL;DR

This paper presents new experimental constraints on composite strongly interacting dark matter using a novel detector, narrowing the viable parameter space for such particles and proposing methods to enhance future sensitivity.

Contribution

It introduces a new detector setup that effectively suppresses backgrounds and sets wide-ranging limits on composite dark matter, expanding the search beyond pointlike candidates.

Findings

Established new limits on composite dark matter interactions

Demonstrated effective background suppression techniques

Outlined strategies for future sensitivity improvements

Abstract

Certain strongly interacting dark matter candidates could have evaded detection, and much work has been done on constraining their parameter space. Recently, it was shown theoretically that the scattering cross section for $m_\chi \gtrsim 1$ GeV pointlike dark matter with a nucleus cannot be significantly larger than the geometric cross section of the nucleus. This realization closes the parameter space for pointlike strongly interacting dark matter. However, strongly interacting dark matter is still theoretically possible for composite particles, with much parameter space open. We set new, wide-ranging limits based on data from a novel detector at the University of Chicago. Backgrounds are greatly suppressed by requiring coincidence detection between two spatially separated liquid-scintillator modules. For dark matter ($v \sim 10^{-3}$c), the time of flight would be $\sim 2~\mu{\rm s}$, whereas for cosmic rays, it would be $\sim 2~{\rm ns}$. We outline ways to greatly increase sensitivity at modest costs.