Axion Dark Matter Search around 4.55 μeV with Dine-Fischler-Srednicki-Zhitnitskii Sensitivity

We report an axion dark matter search at Dine-Fischler-Srednicki-Zhitnitskii sensitivity with the CAPP-12TB haloscope, assuming axions contribute 100% of the local dark matter density. The search excluded the axion-photon coupling ${g}_{a\ensuremath{\gamma}\ensuremath{\gamma}}$ down to about $6.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}16}\text{ }\text{ }{\mathrm{GeV}}^{\ensuremath{-}1}$ over the axion mass range between 4.51 and $4.59\text{ }\text{ }\mathrm{\ensuremath{\mu}}\mathrm{eV}$ at a 90% confidence level. The achieved experimental sensitivity can also exclude Kim-Shifman-Vainshtein-Zakharov axion dark matter that makes up just 13% of the local dark matter density. The CAPP-12TB haloscope will continue the search over a wide range of axion masses.