Sum rules for CP-violating operators of Weinberg type

TL;DR

This paper estimates the hadronic matrix elements of CP-violating Weinberg operators using sum-rule techniques, providing new results for four-gluon operators and a systematic study of their impact on neutron electric dipole moments.

Contribution

It introduces the first systematic analysis of four-gluon Weinberg operators and details the sum-rule derivation and uncertainty analysis for these CP-violating contributions.

Findings

Reproduces known three-gluon operator results

Provides new estimates for four-gluon operator matrix elements

Analyzes uncertainties in sum-rule predictions

Abstract

We estimate the size of the hadronic matrix elements of CP-violating three-gluon and four-gluon Weinberg operators using sum-rule techniques. In the three-gluon case, we are able to reproduce the expressions given in earlier works, while the four-gluon results obtained in this article are new. Our paper therefore represents the first systematic study of contributions to the electric dipole moment of the neutron due to CP-violating dimension-six and dimension-eight operators. We provide many details on both the derivation of the sum rules as well as the analysis of the uncertainties that plague our final predictions.