Radiative decays, photoproduction and total cross section of the Psi particles

It is pointed out that the coupling characterizing the psi - γ vertex must change substantially between the limits, psi on mass-shell which occurs in psi→e+e-and photon on mass-shell which is relevant in radiative decays like psi→ππγ, psi→etaγ and photo-production of psi. This has the consequence that the value of psi N total cross-section must be larger than what is inferred from the use of naive vector dominance in photo-production. (author)