Quenching effects in strong penguin contributions to $\epsilon'/\epsilon$

TL;DR

This paper investigates the impact of quenching effects on strong penguin contributions to the CP violation parameter '/, revealing a large constant in quenched ChPT and revisiting previous lattice analyses.

Contribution

It provides a lattice determination of _q^{NS} and assesses how quenching methods affect the calculation of '/ in lattice QCD.

Findings

The constant _q^{NS} is found to be large.

Quenching methods significantly influence the matrix element calculations.

Reevaluation of the RBC analysis with new quenching insights.

Abstract

Quenching effects in strong penguin matrix elements are investigated. A lattice determination of $\alpha_q^{NS}$, the constant that appears in the quenched ChPT relevant for the lattice analysis of $K\to\pi\pi$ matrix elements, shows that this constant is large. The original RBC analysis of $Q_6$ matrix elements is revisited in light of this result. Also, the numerical effects of choosing the singlet Golterman-Pallante method of quenching $Q_6$ is investigated.