Constraining short-range spin-dependent forces with polarized helium 3 at the Laue-Langevin Institute

TL;DR

This paper investigates the existence of short-range spin-dependent forces by analyzing the spin relaxation of hyperpolarized helium-3, aiming to detect effects from hypothetical light scalar bosons with CP-violating neutron couplings.

Contribution

It introduces a novel experimental approach to constrain short-range spin-dependent interactions using polarized helium-3 and wall-induced pseudomagnetic fields.

Findings

No evidence of the hypothesized interaction was observed.

Established new upper limits on the strength of short-range spin-dependent forces.

Demonstrated the sensitivity of helium-3 spin relaxation measurements for fundamental physics searches.

Abstract

We have searched for a short-range spin-dependent interaction mediated by a hypothetical light scalar boson with CP-violating couplings to the neutron using the spin relaxation of hyperpolarized $^3$He. The walls of the $^3$He cell would generate a depolarizing pseudomagnetic field.