Rare Kaon Decays at CERN SPS

Since their discovery the K‐mesons continue to provide valuable information to the theory of the interactions between the elementary particles. In two years of data taking the NA48/2 experiment at CERN SPS recorded more than 4 billion K±→π+π−π± decays devoted to the search of CP violation in the charged kaon system. The huge statistics allows also a precise study of rare kaon decays. The results from the investigation of K±→π±e+e− decay will be shown with their interpretation within several theoretical models. The continuation of the kaon program at CERN is the NA62 experiment devoted to the measurement of Br(K±→π±vν) decay with a precision of 10% in two years of data taking. The planned detector setup and the expected background and signal events will be presented. During 2007 a dedicated run devoted to NA62 prototype tests and study of Ke2 decays was taken. The preliminary results from the study of Ke2 decays and the ratio RK = Γ(K±→e±ν)/Γ(K±→μ±μ) at the NA48/2 and NA62 experiments will be shown.