Using Earth to Search for Long-Range Spin-Velocity Interactions

TL;DR

This paper combines laboratory spin coupling measurements with Earth modeling to set new limits on long-range spin-velocity interactions mediated by ultralight or massless bosons, advancing constraints on physics beyond the standard model.

Contribution

It introduces a novel approach of integrating Earth models with experimental data to constrain long-range spin-velocity couplings for various fermions.

Findings

Established new upper bounds on spin-velocity couplings.

Constrained interactions mediated by ultralight or massless bosons.

Improved limits on physics beyond the standard model.

Abstract

Precision measurements of the possible coupling of spin to other scalars, vectors and pseudovectors has proven to be a sensitive way to search for new particle physics beyond the standard model. Indeed, in addition to searching for exotic spin-spin interactions, studies have been undertaken to look for couplings of spin to gravity, the relative velocity between particles, and preferred directions. Several laboratory experiments have established upper bounds on the energy associated with various fermion spin-orientations relative to Earth. Here, we combine these results with a model of Earth in order to investigate the possible long-range spin-velocity interactions associated with the exchange of ultralight ($m_{z'}<1$ neV) or massless scalar or vector bosons. We establish stringent bounds on the strength of these couplings between electrons, neutrons, protons and nucleons.