Scattering of light dark matter in atomic clocks

TL;DR

This paper analyzes how light dark matter particles scattering off atoms can cause measurable frequency shifts in atomic clocks, offering a new way to constrain dark matter models in the sub-GeV mass range.

Contribution

It provides a detailed theoretical framework for detecting light dark matter via atomic clock frequency shifts caused by scattering, focusing on the low-mass regime.

Findings

Frequency shifts are first order in scattering amplitudes.

Atomic clocks can constrain dark matter models with non-zero differential scattering amplitudes.

Order of magnitude estimates suggest potential sensitivity to light dark matter.

Abstract

We present a detailed analysis of the effect of light Dark Matter (DM) on atomic clocks, for the case where DM mass and density are such that occupation numbers are low and DM must be considered as particles scattering off the atoms, rather than a classical field. We show that the resulting atomic clock frequency shifts are first order in the scattering amplitudes, and particularly suited to constrain DM models in the regime where the DM mass $m_\chi \ll$ GeV. We provide some rough order of magnitude estimates of sensitivity that can be confronted to any DM model that allows for non zero differential scattering amplitudes of the two atomic states involved in the clock.