Weakly-induced strong CP-violation

TL;DR

This paper revisits weak interaction effects on the strong CP-violation parameter using large-Nc Chiral Perturbation Theory, providing a precise estimate of the correction magnitude.

Contribution

It introduces a novel calculation of second-order weak contributions to the strong theta parameter within a large-Nc Chiral Perturbation Theory framework.

Findings

Estimated weak contribution to theta parameter as approximately 10^{-17}.

Expressed CP-violating effects in K to pi pi decays in terms of hadronic amplitudes.

Provides a refined theoretical understanding of weak effects on strong CP-violation.

Abstract

Weak interaction contributions to the strong theta parameter are revisited in the frame of a large-Nc Chiral Perturbation Theory. Focusing on the hadronic (eta,etaprime) \to pi pi amplitudes, we express these second-order corrections in terms of the CP-violating parameter in K \to pi pi decays to obtain Delta_w(theta) approx 10^{-17} at O(GF^2 epsilonprime).