High-mass axion haloscope experiments using novel cavity designs at IBS-CAPP*

The axion is a pseudo-Goldstone boson that elegantly explains the strong CP problem, a long-standing topological problem in the strong interaction. In particular, invisible axions with masses on the order of ueV to meV are strong candidates for dark matter. The cavity haloscope is currently the most sensitive method to search for dark matter axions in the microwave region, but the detection efficiency decreases with increasing mass. Recently, various novel cavity designs (based on multiple cells, wheel mechanism, and tunable photonic crystals) have been proposed by IBS-CAPP for effective searches for high-mass axions. By incorporating these designs, IBS-CAPP plans to conduct leading haloscope searches in the mass region up to 100 ueV (25 GHz in frequency). Appropriate cavities have been designed for different target masses, and several experiments with near KSVZ sensitivity are either ongoing or under preparation. In this talk, we present the current status of these experiments and discuss future plans.