Electromagnetic Structure of the Pion and the Kaon

We study the electromagnetic structure of the pseudoscalar Goldstone bosons ($\pi ,K$) in the framework of a generalized $\mathrm{SU}{\mathrm{}\left(3\right)\mathrm{}}_f$ Nambu-Jona-Lasinio model. Including vector-meson contributions beyond the Hartree-Fock approximation the $q^2$ dependence of the electromagnetic form factors in the spacelike region is well reproduced. We also find that $〈r_K^2+〉<〈r_{\pi }^2+〉$, in agreement with the data.