Eur. Phys. J. C 22, 715-726 (2002)
https://doi.org/10.1007/s100520100824

Charged-lepton-flavour violation in kaon decays in supersymmetric theories

¹ Skobeltsyn Institute for Nuclear Physics, Moscow State University, 119 899 Moscow, Russia
² Centre for Space Research and Technologies, Faculty of Physics, University of Sofia, 1164~Sofia, Bulgaria
³ Theory Division, CERN, 1211 Geneva 23, Switzerland
⁴ Bogoliubov Laboratory for Theoretical Physics, Joint Institute for Nuclear Research, 141 980 Dubna, Russia
⁵ CFIF, Departamento de Fisica, Instituto Superior T\'ecnico, Av. Rovisco Pais, 1049-001~Lisboa, Portugal

Received: 8 September 2000
Published online: 17 December 2001

Abstract

We discuss rare kaon decays that violate charged-lepton flavour conservation in supersymmetric theories with and without R parity, in view of possible experiments using an intense proton source as envisaged for a neutrino factory. In the minimal supersymmetric standard model, such decays are generated by box diagrams involving charginos and neutralinos, but the limits from μ → eγ, μ-e conversion and Δm_K constrain the branching ratios to challengingly small values. However, this is no longer the case in R-violating theories, where such decays may occur at tree level at rates close to the present experimental limits. Within this framework, we obtain bounds on products of LLĒ and LQD operators from the experimental upper limits on K⁰ → μ^± e^± and K^±,0 → π^±,0 μ^± e^± decays. We also note the possibility of like-sign lepton decays K^± → π^± ℓ^± ℓ^± in the presence of non-zero b_L-b_R mixing. We conclude that rare kaon decays violating charged-lepton flavour conservation could be an interesting signature of R violation.