Searches for the axion and axionlike particles may hold the key to unlocking some of the deepest puzzles about our universe, such as dark matter and dark energy. Here we use the recently demonstrated spin-based amplifier to constrain such hypothetical particles within the well-motivated ``axion window'' (1 μeV-1 meV) through searching for an exotic spin-spin interaction between polarized electron and neutron spins. The key ingredient is the use of hyperpolarized long-lived 129Xe nuclear spins as an amplifier for the pseudomagnetic field generated by the exotic interaction. Using such a spin sensor, we obtain a direct upper bound on the product of coupling constants gpegpn. The spin-based amplifier technique can be extended to searches for a wide variety of hypothetical particles beyond the Standard Model.
@article{arxiv.2201.11847,
title = {Limits on axions and axionlike particles within the axion window using a spin-based amplifier},
author = {Yuanhong Wang and Haowen Su and Min Jiang and Ying Huan and Yushu Qin and Chang Guo and Zehao Wang and Dongdong Hu and Wei Ji and Pavel Fadeev and Xinhua Peng and Dmitry Budker},
journal= {arXiv preprint arXiv:2201.11847},
year = {2022}
}