Predictions for the rare kaon decays $K_{S,L}\to {\pi }^0{\ell }^{+}{\ell }^{-}$ from QCD in the limit of a large number of colours

Giancarlo D'Ambrosio, Marc Knecht

The long-distance and non-local parts of the form factors describing the single-photon mediated $K_{S,L}\to {\pi }^0{\gamma }^{\ast }\to {\pi }^0{\ell }^{+}{\ell }^{-}$ ($\ell =e,\mu$) transitions in the standard mod…