A Near-Cutoff Waveguide Haloscope for sub-meV Dark Matter

TL;DR

This paper introduces a novel near-cutoff waveguide haloscope design that enhances field interaction for sub-meV dark matter detection, combining large-area openness with cavity-like effects without traditional resonances.

Contribution

It proposes a new waveguide-based haloscope concept that improves sensitivity for sub-meV dark matter searches by leveraging slow-wave response and coherent accumulation.

Findings

Projected dark photon sensitivity of ε ≈ 2.1×10⁻¹⁵ near 0.1 meV

Design can approach QCD axion parameter space with an external magnetic field

Highlights a scalable approach for future sub-meV bosonic dark matter searches

Abstract

We propose a near-cutoff parallel-plate waveguide haloscope for sub-meV dark matter. The concept retains the large-area openness of a dish antenna while providing cavity-like field enhancement through slow-wave response and coherent accumulation, without relying on a closed standing-wave resonance. For a copper waveguide, the projected dark photon sensitivity reaches $\varepsilon\simeq2.1\times10^{-15}$ near $m_{A'}\simeq 0.1\,\mathrm{meV}$. With an external magnetic field, the same transducer can approach QCD axion parameter space. The waveguide haloscope highlights a sensitive and scalable route toward future sub-meV bosonic dark matter searches.