On PSI-meson photoproduction

Possible reasons for smallness of PSI-meson photoproduction cross section are discussed: i) the real PSI-meson-nucleon scattering cross section is small to the small value of the pomeron residue; ii) because of its large mass the virtual psi-meson cannot develop the pomeron shower and thus the diffraction transition of a virtual PSI with q2=0 into real one with q2=msub(phi)sup(2) is small; iii) the transition PSI → γ is small while the vertex Gsub(e)PSIsub(μ)anti eγsub(μ)e is a fundamental one so that PSI → e+e- decays does not proceed through the virtual photon. It is shown that one can distinguish between these possibilities through experimental studies of the PSI-mesons electroproduction and their photoproduction on nuclei