Direct CP Violation in Charged Kaon Decays by the NA48/2 Experiment at CERN

The NA48/2 experiment at CERN is performing high precision studies of charged kaon decays, using an upgraded NA48 setup and a novel design for simultaneous unseparated K± beams. The main goal is to search for direct CP violation in decays to three pions with a sensitivity at a level of 10−4 on the asymmetry Ag=(g+−g−)/(g++g−) where g is the linear slope parameter in the Dalitz plot. The experimental procedure and the main systematic effects are discussed, based on the preliminary analysis of a fraction (less than 50%) of the data recorded. The statistical errors on the K±→π+π−π± and K±→π0π0π± asymmetries are 2.7×10−4 and 5×10−4, respectively. The large amount of charged kaon decays collected allow also precision measurements of several rare decay processes.