Searching for Scalar Field Dark Matter using Cavity Resonators and Capacitors

TL;DR

This paper proposes new experimental methods using cavity resonators and capacitors to search for scalar field dark matter, providing improved sensitivity and new limits on scalar-photon coupling based on existing and novel setups.

Contribution

It introduces a novel broadband experiment with capacitors and re-purposes existing cavity resonator data to set new limits on scalar field dark matter.

Findings

Existing cavity resonators have non-zero sensitivity to scalar-photon coupling.

Re-analysis of ADMX data yields new limits on scalar-photon coupling for masses 2.7-4.2 μeV.

Capacitor-based experiment surpasses molecular spectroscopy sensitivity by nearly two orders of magnitude.

Abstract

We establish new experiments to search for dark matter based on a model of a light scalar field with a dilaton-like coupling to the electromagnetic field, which is strongly motivated by superstring theory. We estimate the power of the photon signal in the process of a non-resonant scalar-photon transition and in a cavity resonator permeated by electric and magnetic fields. We show that existing cavity resonators employed in the experiments like ADMX have a low but non-vanishing sensitivity to the scalar-photon coupling. As a result, by re-purposing the results of the ADMX experiment, we find new limits on the scalar-photon coupling in the range of the scalar field masses from 2.7 to 4.2 $\mu$eV. We discuss possible modifications of this experiment, which enhance the sensitivity to the scalar field dark matter. We also propose a broadband experiment for scalar field dark matter searches based on a high-voltage capacitor. The estimated sensitivity of this experiment exceeds by nearly two orders in magnitude the sensitivity of the experiment based on molecular spectroscopy.