A New Estimate of $\varepsilon '/\varepsilon$

TL;DR

This paper presents a new theoretical estimate of the direct CP violation parameter '/ in the kaon system, utilizing a chiral quark model with meson loop corrections and NLO Wilson coefficients.

Contribution

It introduces a consistent method for calculating '/ that aligns with the =1/2 rule in kaon decays, improving previous estimates.

Findings

Estimate aligns with experimental data

Reproduces the =1/2 rule within the model

Incorporates meson one-loop renormalization and NLO effects

Abstract

We discuss a new estimate of $\varepsilon '/\varepsilon$ in the kaon system. The present approach is based on the evaluation of the hadronic matrix elements of the \mbox{$\Delta S =1$} effective quark lagrangian by means of the chiral quark model, with the inclusion of meson one-loop renormalization and NLO Wilson coefficients. The estimate here reviewed is fully consistent with the $\Delta I =1/2$ selection rule in $K\to \pi\pi$ decays, which is well reproduced within the same framework.