High precision study of CP-violating charge asymmetry in K+- --> 3pi+- decays

TL;DR

This paper reports a highly precise measurement of CP violation in charged kaon decays, using a large dataset to improve the accuracy of the charge asymmetry parameter $A_g$ with minimal systematic uncertainties.

Contribution

The study provides the most precise measurement to date of the direct CP violating charge asymmetry in $K^ o o o$ decays, utilizing the NA48/2 experiment at CERN with a large event sample.

Findings

Measured $A_g = (-1.3 imes 10^{-4}) ext{ with } ext{uncertainty } ext{±} 2.3 imes 10^{-4}$

Achieved a result limited by statistical uncertainties rather than systematics

Set constraints on CP violation parameters in kaon decays.

Abstract

A precise measurement of the direct CP violating charge asymmetry parameter $A_g$ in $K^\pm\to\pi^\pm\pi^+\pi^-$ decays by the NA48/2 experiment at CERN SPS is presented. The experiment has been designed not to be limited by systematic uncertainties in the asymmetry measurement. A preliminary result for the charge asymmetry $A_g=(-1.3\pm2.3)\times 10^{-4}$ has been obtained with a sample of $3.11\times 10^9$ selected events corresponding to the full collected statistics. The precision of the result is limited by the statistics used.