New Limit on Axionlike Dark Matter Using Cold Neutrons.

We report on a search for dark matter axionlike particles (ALPs) using a Ramsey-type apparatus for cold neutrons. A hypothetical ALP-gluon coupling would manifest in a neutron electric dipole moment signal oscillating in time. Twenty-four hours of data have been analyzed in a frequency range from 23 µHz to 1 kHz, and no significant oscillating signal has been found. The usage of present dark-matter models allows one to constrain the coupling of ALPs to gluons in the mass range from 10^{-19} to 4×10^{-12} eV. The best limit of C_{G}/f_{a}m_{a}=2.7×10^{13} GeV^{-2} (95% C.L.) is reached in the mass range from 2×10^{-17} to 2×10^{-14} eV.