Rare K Decays: Present and perspectives with NA62

Abstract

Rare kaon decays provide unique opportunity to test the Standard Model and probe its possible extensions. The final result on the lepton universality test by measuring the ratio R_K = G(K+- to e+- nu)/G(K+- to mu+- nu) is presented as well as the status of the study of the rare decays K+- to pi+- gamma gamma and K+ to e+ nu gamma. The primary goal of the NA62 experiment is the measurement of the Br(K+ to pi+ nu anti-nu) decay with a precision of 10% in two years of data taking. The detector setup together with the analysis technique is described.