Search for direct CP violation in the decays K\pm \to 3\pi\pm

TL;DR

This paper reports a precise measurement of direct CP violation in charged kaon decays, finding no significant asymmetry within the experimental uncertainties, thus providing important constraints on CP violation models.

Contribution

The study presents the first high-precision measurement of the CP asymmetry parameter in K± to 3π± decays using a large data sample from NA48/2 at CERN.

Findings

Measured asymmetry parameter A_g = (1.7 ± 2.9) × 10^{-4}

Result limited by statistical uncertainties

No evidence of direct CP violation observed

Abstract

We report a measurement of the direct CP violation asymmetry parameter $A_g$ in charged kaon decays $K^\pm\to\pi^\pm\pi^+\pi^-$ by the NA48/2 experiment at the CERN SPS. The experiment has been designed not to be limited by systematics in the asymmetry measurement. Using $1.67\times 10^9$ such decays collected during the 2003 run, the charge asymmetry in the Dalitz plot linear slope parameter $g$ has been measured to be $A_g=(1.7\pm2.9)\times 10^{-4}$. The precision of the result is limited by the statistics used.