Kaon physics can test new-physics effects in leptonic or semileptonic decays. A unitarity test of the first row of the CKM mixing matrix is obtained from the precision measurements of Kl3 widths for K{pm}, KL, and (unique to KLOE) KS. The KLOE measur
ement of RK = {Gamma}(Ke2)/{Gamma}(K{mu}2) with an accuracy at the % level, aims at finding evidence of deviations from the SM prediction induced by lepton-flavor violation new-physics effects.
We present a precise measurement of the ratio R_K = Gamma(Ke2(gamma))/Gamma(Kmu2(gamma)) performed with the KLOE detector. The results are based on data collected at the Frascati e^+e^- collider DAFNE for an integrated luminosity of 2.2 fb^{-1}. We f
ind R_K = (2.493pm0.025_{stat}pm0.019_{syst})times 10^{-5}, in agreement with the Standard Model expectation. This result is used to improve constraints on parameters of the Minimal Supersymmetric Standard Model with lepton flavor violation.
This paper is devoted to the first analyses based on the complete data sample collected by the KLOE detector at DAPHNE, the Frascati phi-factory. The result for the BR(K_S -> gammagamma) and the search for the decay K_S->e+e- are presented. Particula
r emphasis is put on the measurement of the ratio of Ke2 and Kmu2 BRs.
