A precision measurement of direct CP violation in the decay of neutral kaons into two pions

TL;DR

This paper reports a precise measurement of direct CP violation in neutral kaon decays, combining data from multiple years to refine the value of Re(epsilon'/epsilon) and improve understanding of CP symmetry breaking.

Contribution

The paper presents a new, more precise measurement of Re(epsilon'/epsilon) by analyzing additional data collected under varied conditions, enhancing the accuracy of CP violation parameters.

Findings

Re(epsilon'/epsilon) = (14.7 +/- 2.2) x 10^{-4} from combined data

New data from 2001 increased measurement precision

Results support existing evidence of direct CP violation

Abstract

The direct CP violation parameter Re(epsilon'/epsilon) has been measured from the decay rates of neutral kaons into two pions using the NA48 detector at the CERN SPS. The 2001 running period was devoted to collecting additional data under varied conditions compared to earlier years (1997-99). The new data yield the result: Re(epsilon'/epsilon) = (13.7 +/- 3.1) times 10^{-4}. Combining this result with that published from the 1997, 98 and 99 data, an overall value of Re(epsilon'/epsilon) = (14.7 +/- 2.2) times 10^{-4} is obtained from the NA48 experiment.