pi^0-eta Mixing and CP Violation

TL;DR

This paper investigates the effects of $\pi^0$-$\eta$ mixing on CP violation measurements, revealing cancellations at next-to-leading order in the chiral expansion that impact theoretical predictions.

Contribution

It provides a detailed analysis of $\pi^0$-$\eta$ mixing effects on $\epsilon'/\epsilon$ at next-to-leading order, highlighting cancellations with other contributions.

Findings

$\eta$-$\eta'$ mixing significantly affects $\pi^0$-$\eta$ mixing calculations.

Large effects from $\eta$-$\eta'$ mixing are largely canceled by other contributions.

Implications for precise CP violation measurements in kaon decays.

Abstract

We discuss $\pi^0$ -$\eta$ mixing and its implication for $\epsilon'/ \epsilon$ to next-to-leading order in the low-energy expansion. The big effect due to $\eta$-$\eta'$ mixing is shown to be largely cancelled by other contributions occurring at the same order in the chiral expansion.