Searching for an oscillating massive scalar field as a dark matter candidate using atomic hyperfine frequency comparisons

TL;DR

This study uses six years of atomic frequency comparison data to search for oscillating massive scalar dark matter, setting new constraints on its coupling to standard matter by analyzing hyperfine transition ratios.

Contribution

It provides the first comprehensive search for scalar dark matter affecting multiple fundamental constants using atomic hyperfine frequency comparisons.

Findings

No evidence of scalar dark matter detected.

Improved constraints on scalar field coupling by over an order of magnitude.

Constraints are complementary to previous electromagnetic-only limits.

Abstract

We use six years of accurate hyperfine frequency comparison data of the dual rubidium and caesium cold atom fountain FO2 at LNE-SYRTE to search for a massive scalar dark matter candidate. Such a scalar field can induce harmonic variations of the fine structure constant, of the mass of fermions and of the quantum chromodynamic mass scale, which will directly impact the rubidium/caesium hyperfine transition frequency ratio. We find no signal consistent with a scalar dark matter candidate but provide improved constraints on the coupling of the putative scalar field to standard matter. Our limits are complementary to previous results that were only sensitive to the fine structure constant, and improve them by more than an order of magnitude when only a coupling to electromagnetism is assumed.