KN Scattering and the Nucleon Strangeness Radius

Abstract

The leading non-zero electric moment of the nucleon strange-quark vector current is the mean square strangeness radius, $<r_s^2>$. We evaluate the lightest OZI-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 $e^{+}{e}^{-}\to K\bar{K}$ 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 $\varphi$-meson resonance which may enhance the scale of kaon cloud contribution to an observable level.

Comments: 4 pages, RevTex, 1 PS figure, uses epsf.sty, revised to improve clarity, results unchanged