Reexamination of The Standard Model Nucleon Electric Dipole Moment

TL;DR

This paper provides an updated theoretical calculation of the nucleon electric dipole moment within the Standard Model, addressing previous issues and estimating its magnitude based on recent methods and constants.

Contribution

It offers a re-analysis using Heavy Baryon Chiral Perturbation Theory that preserves power counting and incorporates recent low energy constant determinations.

Findings

Estimated nucleon EDM: (1×10^{-32} - 6×10^{-32}) e·cm

Addresses theoretical issues in previous calculations

Uses updated chiral perturbation theory methods

Abstract

The Cabibbo-Kobayashi-Maskawa matrix in the Standard Model is currently the only experimentally-confirmed source of CP-violation. The intrinsic electric dipole moment of the nucleon induced by this CP-phase via hadronic loop and pole diagrams has been studied more than two decades ago, but the existing calculation is subject to various theoretical issues such as the breakdown of chiral power counting and uncertainties in the determination of low energy constants. We carry out an up-to-date re-analysis on both one-loop and pole diagram contributions to the nucleon electric dipole moment based on Heavy Baryon Chiral Perturbation Theory in a way that preserves power counting, and redo the determination of the low energy constants following the results of more recent articles. Combined with an estimation of higher-order contributions, we expect the long-distance contribution to the Standard Model nucleon electric dipole moment to be approximately $(1\times10^{-32}-6\times10^{-32})e\,\mathrm{cm}$.