Experimental Search for Invisible Dark Matter Axions around 22 μeV.

The axion has emerged as the most attractive solution to two fundamental questions in modern physics related to the charge-parity invariance in strong interactions and the invisible matter component of our Universe. Over the past decade, there have been many theoretical efforts to constrain the axion mass based on various cosmological assumptions. Interestingly, different approaches from independent groups produce good overlap between 20 and 30  μeV. We performed an experimental search to probe the presence of dark matter axions within this particular mass region. The experiment utilized a multicell cavity haloscope embedded in a 12 T magnetic field to seek for microwave signals induced by the axion-photon coupling. The results ruled out the KSVZ axions as dark matter over a mass range between 21.86 and 22.00  μeV at a 90% confidence level. This represents a sensitive experimental search guided by specific theoretical predictions.