Searching for Dark Absorption with Direct Detection Experiments

TL;DR

This paper evaluates the potential of current and future direct detection experiments to identify dark matter particles like dark photons and axion-like particles through electron recoil signals, updating bounds and projecting new sensitivities.

Contribution

It provides updated constraints on dark photon dark matter from existing experiments and projects future sensitivities for upcoming detectors, exploring new parameter space regions.

Findings

Current experiments disfavor previously allowed dark photon parameter space.

Projected experiments can explore large new regions of dark matter parameter space.

Some sensitivities can probe parameter space hinted at by white dwarf observations.

Abstract

We consider the absorption by bound electrons of dark matter in the form of dark photons and axion-like particles, as well as of dark photons from the Sun, in current and next-generation direct detection experiments. Experiments sensitive to electron recoils can detect such particles with masses between a few eV to more than 10 keV. For dark photon dark matter, we update a previous bound based on XENON10 data and derive new bounds based on data from XENON100 and CDMSlite. We find these experiments to disfavor previously allowed parameter space. Moreover, we derive sensitivity projections for SuperCDMS at SNOLAB for silicon and germanium targets, as well as for various possible experiments with scintillating targets (cesium iodide, sodium iodide, and gallium arsenide). The projected sensitivity can probe large new regions of parameter space. For axion-like particles, the same current direction detection data improves on previously known direct-detection constraints but does not bound new parameter space beyond known stellar cooling bounds. However, projected sensitivities of the upcoming SuperCDMS SNOLAB using germanium can go beyond these and even probe parameter space consistent with possible hints from the white dwarf luminosity function. We find similar results for dark photons from the sun. For all cases, direct-detection experiments can have unprecedented sensitivity to dark-sector particles.