Vector-meson production and vector meson dominance

We consider the fidelity of vector meson dominance (VMD) assumption as an instrument for relating electromagnetic vector-meson production reaction $e + p \to e^\prime V p$ to purely hadronic process $V V+p$. Analyses photon vacuum polarisation and photon-quark vertex reveal that such a VMD Ansatz might be reasonable light vector-mesons. However, when vector-mesons are described by momentum-dependent bound-state amplitudes, fails heavy vector-mesons: it cannot used reliably estimate either photon-to-vector-meson transition strength or momentum dependence those integrands would arise in calculations different amplitudes. Consequently, processes involving mesons, veracity both cross-section estimates conclusions based on should reviewed, e.g., hidden-charm pentaquark origin proton mass.