Extended Search for the Invisible Axion with the Axion Dark Matter Experiment

Abstract

This paper reports on a cavity haloscope search for dark matter axions in the galactic halo in the mass range $2.81$-$3.31$ $\hat{I}¼eV$. This search excludes the full range of axion-photon coupling values predicted in benchmark models of the invisible axion that solve the strong CP problem of quantum chromodynamics, and marks the first time a haloscope search has been able to search for axions at mode crossings using an alternate cavity configuration. Unprecedented sensitivity in this higher mass range is achieved by deploying an ultra low-noise Josephson parametric amplifier as the first stage signal amplifier.