Strong CP problem

Nuclear physics

Particle physics

Astrophysics

Axion

Physics

Quantum chromodynamics

Dark matter

Universe

Physical Review Letters

Two of the most pressing questions in physics are the microscopic nature of the dark matter that comprises 84% of the mass in the Universe and the absence of a neutron electric dipole moment. These questions would be resolved by the existence of a hypothetical particle known as the quantum chromodynamics (QCD) axion. In this work, we probe the hypothesis that axions constitute dark matter, using the ABRACADABRA-10 cm experiment in a broadband configuration, with world-leading sensitivity. We find no significant evidence for axions, and we present 95% upper limits on the axion-photon coupling down to the world-leading level ${g}_{a\ensuremath{\gamma}\ensuremath{\gamma}}&lt;3.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}11}\text{ }\text{ }{\mathrm{GeV}}^{\ensuremath{-}1}$, representing one of the most sensitive searches for axions in the 0.41--8.27 neV mass range. Our work paves a direct path for future experiments capable of confirming or excluding the hypothesis that dark matter is a QCD axion in the mass range motivated by string theory and grand unified theories.

Search for Low-Mass Axion Dark Matter with ABRACADABRA-10 cm