Exclusive production of vector mesons ρ, ρ′ and ρ" by real and virtual photons

We present a non-perturbative QCD calculation of high-energy diffractive photo- and leptoproduction of vector mesons rho, rho' and rho " on a nucleon. The initial photon splits up in a q (q) over bar-dipole and transforms into a Vector meson by scattering on the quark-diquark nucleon. The dipole-dipole scattering amplitude is provided by the non-perturbative model of the stochastic QCD vacuum, the wave functions result from considerations on the light-cone. We assume the physical rho'- and rho "-states to be mixed states of an active 2S-excitation and a rest whose coupling to the photon is suppressed. We obtain good agreement with the experimental data and get an understanding of the markedly different spectrum in the pi(+)pi(-)-invariant mass for photoproduction and e(+)e(-)-annihilation.