Contributions of $K\bar{K}$ Intermediate State to Nucleon Form Factors

Abstract

An attempt is made to estimate the contribution of KK intermediate state to nucleon form factor, using an approximate representation for K-N scattering and form factor of kaon under bi-pion and tri-pion approximations of γ-K vertex. The representation for K-N scattering is obtained under the assumption that this scattering is dominated by Λ and Σ poles and Y0*, Y1*, ρ, and ω resonances. An effective range analysis is performed to determine the contribution from Y* terms and also to estimate some coupling constants needed in the calculation. PKNΛ and PKNΣ are assumed odd and Y0* and Y1* are assigned spins 1/2 and 3/2, respectively. Our results show that KK contributions to nucleon form factors are quite small, thus confirming the results of previous calculation based on perturbation theory. This is particularly significant in view of the fact that the form factors of kaon, as obtained here, are quite large. Yet our conclusion cannot be taken too seriously because we cannot be sure of the validity of our K-N scattering representation.