Measurement of the FCNC decays K+- --> pi+- l+ l- by the NA48/2 experiment at CERN

Abstract

A sample of 7253 $K^\pm\to\pi^\pm e^+e^-$ decay candidates with 1.0% background contamination has been collected by the NA48/2 experiment at the CERN SPS, which allowed a precise measurement of the form factor, the branching ratio, and the CP violating asymmetry of $K^+$ and $K^-$ decay widths was investigated. The results of the $K^\pm\to\pi^\pm e^+e^-$ analysis, as well as the status of the $K^\pm\to\pi^\pm\mu^+\mu^-$ analysis based in the same data set, are reported.