KNScattering and the Nucleon Strangeness Radius

The leading nonzero electric moment of the nucleon strange-quark vector current is the mean square strangeness radius $〈r_s^2〉$. We evaluate the lightest Okubo-Zweig-Iizuka–allowed contribution to $〈r_s^2〉$, arising from the kaon cloud, using dispersion relations. Drawing upon unitarity constraints as well as $K^{+}N$ scattering and $e^{+}{e}^{-}\to K\overline{K}$ cross section data, we find the structure of this contribution differs significantly from that suggested by a variety of QCD-inspired model calculations. In particular, we find evidence for a strong $\phi$-meson resonance which may enhance the scale of kaon cloud contribution to an observable level.