Axion-like Relics: New Constraints from Old Comagnetometer Data

Understand

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.