New Limits on Ultralight Axionlike Dark Matter

Abstract: New limits on the axion-nucleon coupling over the axion mass region $10^{-24} \leq m_a \leq 5 \times 10^{-21}$ eV are derived by reanalyzing data from laboratory measurements on Lorentz and $CPT$ violation. These results establish the first laboratory constraints on the axion-nucleon coupling for axion masses below $10^{-22}$ eV. For $10^{-22} \leq m_a \leq 5 \times 10^{-21}$ eV, the results improve upon previous laboratory limits by more than 3 orders of magnitude, exceeding for the first time the astrophysical limits from supernova SN1987A cooling. For the axion mass range of interest corresponding to ultralow frequencies, the crucial initial phase of the axion field is considered. Furthermore, the obtained limits are nearly equivalent to those projected for a recently proposed experiment employing high-intensity neutron beams at the European Spallation Source [Phys. Rev. Lett. 133, 181001 (2024)]. For an alternative type of axion-nucleon interaction, the quadratic wind coupling, the constraints exceed the current best results by approximately 2 orders of magnitude.