The exclusive production of vector mesons in deep inelastic scattering is a
hard scattering process with the well controlled size of quark configurations
which dominate the production amplitude. This allows an unambiguous prediction
of color transparency effects in the coherent and incoherent production of
vector mesons on nuclei. We demonstrate how the very mechanism of color
transparency leads to a belated onset of color transparency effects as a
function of Q2. We conclude that the Q2 dependence of the exclusive
ρ0-meson production on nuclei and nucleons observed in the Fermilab
E665 experiment gives a solid evidence for the onset of color transparency. We
propose the scaling relation between the ρ0 and the J/Ψ
production, which further tests the mechanism of color transparency in
exclusive (virtual) photoproduction.Comment: 11 pages, 4 figures on the request from
[email protected], Juelich preprint KFA-IKP(Th)-1993-27.
\phantom{.}\hspace{9cm}{\sl 8 November 1993