SUSY contributions to the charge asymmetry in K^+- -> pi^+- l^+ l^- decays

Abstract

We analyse the contributions to the charge asymmetry in $K^\pm\to\pi^\pm\ell^+\ell^-$ decays induced by gluino-exchange diagrams in the context of supersymmetric models with generic flavour couplings. We show that sizeable deviations with respect to the Standard Model are possible only under special circumstances. Within this scenario we set an upper limit of about $10^{-3}$ for the relative charge asymmetry -- integrated for $M_{\ell^+\ell^-} > 2 M_\pi$ -- of both muon and electron channels. We also show that this limit is close to saturating a model-independent upper bound on the charge asymmetry derived from the present constraints on $\Gamma(K_L \to\pi^0 \ell^+ \ell^-)$.