New Limits on the Couplings of Light Pseudoscalars from Equivalence Experiments

TL;DR

This paper uses equivalence principle experiments to set new, more stringent limits on the coupling strength of light pseudoscalars to nucleons, improving previous bounds by analyzing long-range forces.

Contribution

It introduces a novel method to constrain pseudoscalar couplings by leveraging equivalence principle tests sensitive to spin-independent forces.

Findings

Laboratory bounds on pseudoscalar-nucleon couplings are significantly improved.

Results constrain pseudoscalar interactions more tightly than previous experiments.

Long-range forces from two-pseudoscalar exchange are key to these bounds.

Abstract

The exchange of light pseudoscalar quanta between fermions leads to long-range spin-dependent forces in order g^2, where g is the pseudoscalar-fermion coupling constant. We demonstrate that laboratory bounds on the Yukawa couplings of pseudoscalars to nucleons can be significantly improved using results from recent equivalence principle experiments, which are sensitive to the spin-independent long-range forces that arise in order g^4 from two-pseudoscalar exchange.