Constraining Spacetime Nonmetricity with Neutron Spin Rotation in Liquid He-4

TL;DR

This paper investigates how spacetime nonmetricity affects neutron spin rotation in liquid helium, setting new experimental limits on nonmetricity parameters using neutron propagation data.

Contribution

It provides the first constraints on the nonmetricity component _2S_{000} within matter through neutron spin rotation measurements.

Findings

Constraints on isotropic nonmetricity components at the level of 10^{-22} GeV.

First limit established on the nonmetricity _2S_{000} parameter.

First measurement of nonmetricity effects inside matter.

Abstract

General spacetime nonmetricity coupled to neutrons is studied. In this context, it is shown that certain nonmetricity components can generate a rotation of the neutron's spin. Available data on this effect obtained from slow-neutron propagation in liquid helium are used to constrain isotropic nonmetricity components at the level of $10^{-22}\,$GeV. These results represent the first limit on the nonmetricity $\zeta^{(6)}_2S_{000}$ parameter as well as the first measurement of nonmetricity inside matter.