Search for Spin-Dependent Short-Range Force Using Optically Polarized $^3$He Gas

TL;DR

This paper introduces a novel method using optically polarized $^3$He gas to detect short-range P- and T- violating interactions between nucleons by measuring nuclear precession frequency shifts near unpolarized masses.

Contribution

It presents a new experimental approach with high-pressure $^3$He cells and magnetic field control to improve sensitivity to short-range spin-dependent forces.

Findings

Achieved sensitivity comparable to current best limits without magnetic shielding.

Potential to improve sensitivity by two orders of magnitude with better field stability.

Demonstrated feasibility of detecting short-range P- and T- violating interactions.

Abstract

We propose a new method to detect short-range \textit{P-} and \textit{T-} violating interactions between nucleons, based on measuring the precession frequency shift of polarized $^3$He nuclei in the presence of an unpolarized mass. To maximize the sensitivity, a high-pressure $^3$He cell with thin glass windows (250 $\rm\mu m$) is used to minimize the distance between the mass and $^3$He. The magnetic field fluctuation is suppressed by using the $^3$He gas in a different region of the cell as a magnetometer. Systematic uncertainties from the magnetic properties of the mass are suppressed by flipping both the magnetic field and spin directions. Without any magnetic shielding, our result has already reached the sensitivity of the current best limit. With improvement in uniformity and stability of the field, we can further improve the sensitivity by two orders of magnitude over the force range from $10^{-4}-10^{-2}$ m.