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±νν̄) 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±ν) at the NA48/2 and NA62 experiments will be shown.