A Parametrically Enhanced Hidden Photon Search

TL;DR

This paper proposes a method to significantly improve the sensitivity of hidden photon searches using resonant cavity experiments by exploiting the longitudinal mode, enabling detection of weaker signals and expanding the parameter space coverage.

Contribution

It introduces a parametric enhancement technique leveraging the longitudinal mode of hidden photons, which was previously underutilized in experimental searches.

Findings

Enhanced sensitivity in microwave cavity experiments for hidden photon detection.

Potential to explore dark matter regions of hidden photon parameter space.

Significant improvement over existing experimental limits.

Abstract

Many theories beyond the Standard Model contain hidden photons. A light hidden photon will generically couple to the Standard Model through a kinetic mixing term, giving a powerful avenue for detection using "Light-Shining-Through-A-Wall"-type transmission experiments with resonant cavities. We demonstrate a parametric enhancement of the signal in such experiments, resulting from transmission of the longitudinal mode of the hidden photon. While previous literature has focused on the production and detection of transverse modes, the longitudinal mode allows a significant improvement in experimental sensitivity. Although optical experiments such as ALPS are unable to take useful advantage of this enhancement, the reach of existing microwave cavity experiments such as CROWS is significantly enhanced beyond their published results. Future microwave cavity experiments, designed with appropriate geometry to take full advantage of the longitudinal mode, will provide a powerful probe of hidden-photon parameter space extending many orders of magnitude beyond current limits, including significant regions where the hidden photon can be dark matter.