Vector resonances and electromagnetic nucleon structure

Motivated by new, precise magnetic proton form factor data in the timelike reigon, a hybrid vector meson dominance (hVMD) formalism is employed to investigate the significance of excited vector meson rsonances on electromagnetic nucleon structure. We find that the ρ(1700), ω(1600), and two previously unobserved states are required to reproduce the local structure seen in the new LEAR data just above the p bar p threshold. We also investigate sensitivity to the φ meson. The model dependence of our result is tested by introducing an alternative model which couples the isoscalar vector meson states to a hypothetical vector glueball resonance. We obtain nearly identical results from both models, except for GEn(q2) in the spacelike region which is very sensitive to the glueball mass and the effective φNN coupling