How to identify color transparency effects in electroproduction of vector mesons off nuclei

Coherent interference of vector mesons electroproduced off nuclei on different nucleons leads to a Q(2)-dependence in the nuclear transparency at medium energies, which resembles the predictions for the onset of color transparency (CT). We suggest a mapping of the data for different photon energies nu and virtualities Q(2) in a way, which eliminates the undesirable Q(2)-variation and allows to measure a net CT effect. The CT effects are calculated via a multichannel evolution equation for the density matrix, which describes a superposition of different hadronic states produced by a virtual photon and propagating through nuclear matter. The approach is dual to the quark-gluon representation and incorporates effects of CT and of the coherent interference. It solves the color transparency problem for incoherent electroproduction of vector mesons at any photon energy. (C) 1997 Published by Elsevier Science B.V.