The noble-alkali comagnetometer, developed in recent years, has been shown to be a very accurate measuring device of anomalous magnetic-like fields. An ultra-light relic axion-like particle can source an anomalous field that permeates space, allowing for its detection by comagnetometers. Here we derive new constraints on relic axion-like particles interaction with neutrons and electrons from old comagnetometer data. We show that the decade-old experimental data place the most stringent terrestrial constraints to date on ultra-light axion-like particles coupled to neutrons. The constraints are comparable to those from stellar cooling, providing a complementary probe. Future planned improvements of comagnetometer measurements through altered geometry, constituent content and data analysis techniques could enhance the sensitivity to axion-like relics coupled to nucleons or electrons by many orders of magnitude.
@article{arxiv.1907.03767,
title = {Axion-like Relics: New Constraints from Old Comagnetometer Data},
author = {Itay M. Bloch and Yonit Hochberg and Eric Kuflik and Tomer Volansky},
journal= {arXiv preprint arXiv:1907.03767},
year = {2020}
}