Probing dark photons with plasma haloscopes

TL;DR

This paper proposes using plasma haloscopes with metamaterials to detect dark photons as dark matter candidates, overcoming in-medium suppression effects and enabling exploration of a broad mass range with potential modulation signals for identification.

Contribution

It introduces a novel application of plasma haloscopes for dark photon detection, demonstrating their advantage over conventional methods and confirming the absorption rate via thermal field theory.

Findings

Enables resonant absorption of dark photons in the 6-400 μeV mass range.

Uses metamaterials to match plasma frequency with dark photon mass.

Potential to observe daily or annual modulation signals.

Abstract

Dark photons (DPs) produced in the early Universe are well-motivated dark matter (DM) candidates. We show that the recently proposed tunable plasma haloscopes are particularly advantageous for DP searches. While in-medium effects suppress the DP signal in conventional searches, plasma haloscopes make use of metamaterials that enable resonant absorption of the DP by matching its mass to a tunable plasma frequency and thus enable efficient plasmon production. Using thermal field theory, we confirm the in-medium DP absorption rate within the detector. This scheme allows to competitively explore a significant part of the DP DM parameter space in the DP mass range of $6-400$ $\mu$eV. If a signal is observed, the observation of a daily or annual modulation of the signal would be crucial to clearly identify the signal as due to DP DM and could shed light on the production mechanism.