Hunting for Axionlike Dark Matter by Searching for an Oscillating Neutron Electric Dipole Moment

Abstract

We report on a search for ultra-low-mass axion-like dark matter by analysing the ratio of the spin-precession frequencies of stored ultracold neutrons and ${}^{199}$Hg atoms for an axion-induced oscillating electric dipole moment of the neutron and an axion-wind spin-precession effect. No signal consistent with dark matter is observed for the axion mass range $10^{-24}\text{eV}\le m_a\le 10^{-17}\text{eV}$. Our null result sets the first laboratory constraints on the coupling of axion dark matter to gluons, which improve on astrophysical limits by up to 3 orders of magnitude, and also improves on previous laboratory constraints on the axion coupling to nucleons by up to a factor of 40. The results were initially presented in Phys. Rev. X 7, 041034, of which this proceeding is largely a summary.

Comments: 6 Pages, 3 Figures, Proceedings for the Rencontres de Moriond 2018 Electroweak Conference