Loop-induced dark matter direct detection signals from gamma-ray lines

TL;DR

This paper investigates how dark matter annihilation into gamma-ray lines can induce signals in direct detection experiments, revealing unique recoil spectra and comparing sensitivities for different annihilation types.

Contribution

It provides a model-independent analysis of the direct detection cross section from gamma-ray line signals, highlighting non-standard recoil spectra and the potential for future experimental constraints.

Findings

Current direct detection sensitivity is insufficient for s-wave annihilation.

For p-wave annihilation, direct detection constraints are comparable to indirect searches.

Next-generation experiments can test p-wave dark matter scenarios with large di-photon cross sections.

Abstract

Improved limits as well as tentative claims for dark matter annihilation into gamma-ray lines have been presented recently. We study the direct detection cross section induced from dark matter annihilation into two photons in a model-independent fashion, assuming no additional couplings between dark matter and nuclei. We find a striking non-standard recoil spectrum due to different destructively interfering contributions to the dark matter nucleus scattering cross section. While in the case of s-wave annihilation the current sensitivity of direct detection experiments is insufficient to compete with indirect detection searches, for p-wave annihilation the constraints from direct searches are comparable. This will allow to test dark matter scenarios with p-wave annihilation that predict a large di-photon annihilation cross section in the next generation of experiments.