Abstract
Nucleon electromagnetic form factor data in the spacelike and the timelike regions are fitted with a VDM sum of (up to five) isovector and isoscalar pole terms. Finite width effects are included in the ρ and the ρ' terms. The effects of including the ρ' and the ψ(3.1) are studied. We only find good fits when the ρ' is allowed to have a too low mass (1.2-1.4 GeV) and when in addition some of the couplings or other derived quantities disagree with other estimates. We conclude that VDM is unable to describe the data unless one introduces a number of yet unknown mesons, such as ω', ϕ', ρ' (1.2), etc.

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