Nuclear and Particle Physics, Astrophysics and Cosmology, T-2

Confronting the extended Gari-Krumpelmann Vector Dominance Model for the nucleon electromagnetic form factor with new data and extending it to tome-like four-momentum transfers

Earle Lomon
MIT, LANL

Last summer it was shown that the Gari-Krumpelmann vector-meson sominance + asymptotic pQCD model of elastic electron-nucleon form factors, extended to rho and omega mesons and including the width of the rho meson [Lomon 01, 02, 05]. was a good fit to the new polarization data for R_p and R_n as well as the dcs magnetic form factors. New, higher Q, preliminary R_p and R_n and more precise published G_{Mn} data is reasonably fitted by the 05 parameters and a refit to shows moderate change. The simple analytic form of the model invites an extension to the time-like region (Q^2=-q^2<0). For this purpose the previous phenomenological fit to the dispersion relation results for rho->2pion continuum is replaced by the Breit-Wigner form and the progress is refitting is discussed.

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