Axions, originally proposed to resolve the CP problem in the strong interaction, remain a leading dark matter candidate. While cavity haloscopes offer the most sensitive technique for detecting axions, searches have largely been limited to masses below 10 μeV. We report a sensitive search for axion dark matter with masses around 21 μeV, utilizing the TM020 mode of a cylindrical cavity equipped with an innovative tuning mechanism. Our search achieved a sensitivity of 1.7× the Kim-Shifman-Vainshtein-Zakharov benchmark over a 100-MHz range, representing a significant advance in this mass range. These results demonstrate that higher-order modes provide a viable strategy for extending haloscope searches into previously unexplored higher-mass regions.
Bae et al. (Tue,) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: