Probing new physics through μ-e universality in K→lv

The recent NA48/2 improvement on R-K=Gamma(K -> e nu)/Gamma(K ->mu nu) emphasizes the role of K-l2 decays in probing the mu-e universality. Supersymmetric (SUSY) extensions of the Standard Model can exhibit mu-e nonuniversal contributions. Their origin is twofold: those deriving from lepton flavor conserving couplings are subdominant with respect to those arising from lepton flavor violating (LFV) sources. We show that mu-e nonuniversality in K-center dot 2 is quite effective in constraining relevant regions of SUSY models with LFV (for instance, supergravities with a see-saw mechanism for neutrino masses). A comparison with analogous bounds coming from tau LFV decays proves the relevance of the measurement of R-K to probe LFV in SUSY.