Consistent treatment of color transparency effects in diffractive electroproduction of vector mesons off nuclei

Nuclear transparency for incoherent real and virtual photoproduction of vector mesons off nuclei depends crucially on the interplay of the initial-state and final-state interactions. We develop a consistent description of initial-state and final-state interactions based on the coupled-channel multiple-scattering theory. We present detailed predictions for incoherent production of ss̄ and cc̄ mesons. The onset of initial-state interactions is controlled by the production length lP, and we find strong variations of nuclear transparency when lP rises with energy and becomes comparable to the radius of the target nucleus RA. For ss̄ mesons, the regime lP∼RA corresponds to precisely the kinematic range of the HERA-HERMES experiment, whereas for cc̄ mesons the same condition will be met at the ENC electron-nucleus collider at GSI. In spite of the subasymptotic values of Q2 and v, we find a complex pattern of color transparency-induced effects whose experimental study may provide information on several issues relevant to the understanding of QCD, both in the perturbative and nonperturbative regimes.