  At high energy, the photoproduction or electroproduction of Vector Mesons
allow to prepare a beam of quark-antiquark pairs of a given flavor. At high
momentum transfer, the study of the scattering of these pairs on a nucleon
opens up an original window on the quark-gluon structure of hadronic matter,
which may eventually shed light on its gluonic content, on correlations between
quarks and on the van der Walls part of the interaction between hadrons.
