Measurement of Direct CP Violation by NA48

Abstract

The NA48 experiment at the CERN SPS aims to search for direct CP violation in the $K^0$ system through the measurement of ${\rm Re}(\epsilon'/ \epsilon)$ with high accuracy. In 1999 the NA48 collaboration has published its first measuremen based on 1997 data. A new result, based on 1998 and 1999 data, is presented in this article. The result, combined with 1997 data, ${\rm Re}(\epsilon'/\epsilon) = (15.3 \pm 2.6)\times 10^{-4}$, contributes to the precise determination of the size of direct CP violation.