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 ε≃2.1×10−15 near mA′≃0.1meV. 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.
@article{arxiv.2605.15820,
title = {A Near-Cutoff Waveguide Haloscope for sub-meV Dark Matter},
author = {Chuan-Yang Xing and Bin Zhu},
journal= {arXiv preprint arXiv:2605.15820},
year = {2026}
}