Search of spin-dependent fifth forces with precision magnetometry

TL;DR

This study uses precision magnetometry with lead masses and a SQUID sensor to search for spin-dependent fifth forces, setting new constraints over a broad range of distances and demonstrating potential for future exploration.

Contribution

The paper introduces a novel experimental approach combining magnetometry and modulated source masses to improve constraints on spin-dependent fifth forces.

Findings

Set the most stringent limits on spin-mass interactions from 1 cm to 10 m and 10 km to 300 km.

Achieved sensitivity of 53 aT/√Hz with a SQUID magnetometer.

Demonstrated potential to explore longer-range fifth force interactions.

Abstract

Spin-dependent fifth-forces are associated with particles beyond the standard model. In particular, light pseudo-scalar bosons mediate long-range forces, allowing mass to interact with spins. The search of these interactions can be performed by periodically varying the distance between a source mass and a spin ensemble, in order to modulate the force intensity and detect it with precision magnetometry techniques. In our setup the force arises from room temperature lead masses and is detected in a paramagnetic crystal at 4.2\,K, whose magnetisation is monitored by a SQUID-based magnetometer with the sensitivity of $53\,\mathrm{aT/\sqrt{Hz}}$. Our measurement places the most stringent constraints on a spin-mass interaction in the ranges 1\,cm to 10\,m and 10\,km to 300\,km, improving existing limits up to more than two orders of magnitude. We show that this experimental technique may be further leveraged to explore a vast region of the fifth force's parameter space, with an interaction range longer than a few centimetres.