The recent NA48/2 improvement on RK = (K ! eν)/(K ! μν) emphasizes the role of Kl2 decays in probing the μ − e universality. Supersymmetric (SUSY) extensions of the Standard Model can exhibit μ − e non-universal 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 μ−e non-universality in Kℓ2 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 τ LFV decays proves the relevance of the measurement of RK to probe LFV in SUSY.
Probing new physics through mu - e universality in K ---> l nu.
MASIERO, ANTONIO;PARADISI, PARIDE;
2006
Abstract
The recent NA48/2 improvement on RK = (K ! eν)/(K ! μν) emphasizes the role of Kl2 decays in probing the μ − e universality. Supersymmetric (SUSY) extensions of the Standard Model can exhibit μ − e non-universal 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 μ−e non-universality in Kℓ2 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 τ LFV decays proves the relevance of the measurement of RK to probe LFV in SUSY.
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