Precision test of the SM with Kl2 and Kl3 decays at KLOE
Abstract
Kaon decay studies seeking new-physics (NP) effects in leptonic (Kl2) or semileptonic (Kl3) decays are discussed. A unitarity test of the first row of the CKM mixing matrix is obtained from the KLOE precision measurements of Kl3 widths for K+-, KL, and (unique to KLOE) KS, complemented with the absolute branching ratio for the Kmu2 decay. KLOE results lead to constraints for NP models and can probe possible charged Higgs exchange contribution in SM extensions with two Higgs doublets. The main focus in the present document is set on a new measurement of RK=Gamma(Ke2)/Gamma(Kmu2) with an accuracy at the % level, aiming at finding evidence of deviations from the SM prediction induced by lepton-flavor violation NP effects.
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