Precision determination of pion-nucleon coupling constants using effective field theory

TL;DR

This paper presents a highly precise determination of pion-nucleon coupling constants using chiral effective field theory and Bayesian methods, achieving percent-level accuracy and confirming minimal charge dependence.

Contribution

It introduces a novel Bayesian methodology and performs the first comprehensive partial-wave analysis of nucleon-nucleon scattering up to the pion production threshold within chiral EFT.

Findings

Coupling constants determined with percent-level precision.

No significant charge dependence found in the coupling constants.

Advances the development of a precision nuclear force theory.

Abstract

The pion-nucleon coupling constants determine the strength of the long-range nuclear forces and play a fundamental part in our understanding of nuclear physics. While the charged- and neutral-pion couplings to protons and neutrons are expected to be very similar, owing to the approximate isospin symmetry of the strong interaction, the different masses of the up- and down-quarks and electromagnetic effects may result in their slightly different values. Despite previous attempts to extract these coupling constants from different systems, our knowledge of their values is still deficient. In this Letter we present a precision determination of these fundamental observables with fully controlled uncertainties from neutron-proton and proton-proton scattering data using chiral effective field theory. To achieve this goal, we use a novel methodology based on the Bayesian approach and perform, for the first time, a full-fledged partial-wave analysis of nucleon-nucleon scattering up to the pion production threshold in the framework of chiral effective field theory, including a complete treatment of isospin-breaking effects and our own determination of mutually consistent data. The resulting values of the pion-nucleon coupling constants are accurate at the percent level and show no significant charge dependence. These results mark an important step towards developing a precision theory of nuclear forces and structure.