We report the results of a new search for long range spin-dependent interactions using a Rb -21Ne atomic comagnetometer and a rotatable electron spin source based on a SmCo5 magnet with an iron flux return. By looking for signal correlations with the orientation of the spin source we set new constrains on the product of the pseudoscalar electron and neutron couplings gpegpn/ℏc<1.7×10−14 and on the product of their axial couplings gAegAn/ℏc<5×10−42 to a new particle with a mass of less than about 1μeV. Our measurements improve by about 2 orders of magnitude previous constraints on such spin-dependent interactions.
@article{arxiv.1811.03614,
title = {New limits on Anomalous Spin-Spin Interactions},
author = {Attaallah Almasi and Junyi Lee and Himawan Winarto and Marc Smiciklas and Michael V. Romalis},
journal= {arXiv preprint arXiv:1811.03614},
year = {2020}
}