Exclusion of ALP Cogenesis Dark Matter in a Mass Window Above 100 $\mu$eV

TL;DR

The ORGAN Experiment's Phase 1b conducted a high-sensitivity search for axion dark matter in the 107.42-111.93 μeV range, setting new upper bounds and excluding certain axion models with a novel tunable cavity.

Contribution

First use of a tunable rectangular cavity in a high-mass axion search, achieving the most sensitive limits in the 100 μeV range and excluding specific axion-like particle models.

Findings

Excluded axion-photon coupling g_{aγγ} ≥ 4×10^{-12} GeV^{-1} at 95% confidence

Set the best upper bounds to date in the 107-112 μeV range

Demonstrated the effectiveness of a tunable rectangular cavity for high-mass axion searches

Abstract

We report the results of Phase 1b of The ORGAN Experiment, a microwave cavity haloscope searching for dark matter axions in the $107.42-111.93~\mu$eV mass range. The search excludes axions with two-photon coupling $g_{a\gamma\gamma}\geq 4\times 10^{-12}\, \textrm{GeV}^{-1}$ with $95\%$ confidence interval, setting the best upper bound to date and with the required sensitivity to exclude the axion-like particle cogenesis model for dark matter in this range. This result was achieved using a tunable rectangular cavity, which mitigated several practical issues that become apparent when conducting high mass axion searches, and was the first such axion search to be conducted with such a cavity. It also represents the most sensitive axion haloscope experiment to date in the $\sim100~\mu$eV mass region.