Dispersive description of the $K\to \pi {\ell }^{+}{\ell }^{-}$ radiative amplitudes

Véronique Bernard, Sébastien Descotes-Genon, Marc Knecht +1

We propose a description of the $K^{+}$, $K_S$ radiative decay form factors $W_{+}$, $W_S$ based on general properties of analyticity and unitarity. Starting from the simple considerat…