Nuclear physics at small distances

We report on the study of meson and resonance production in nuclear collisions near the threshold. Because of the large momentum transfer, these reactions occur at length scales less than the size of the hadrons. We explore whether they are best described in terms of the quark-gluon picture or the meson-exchange picture. Comparing our results with the available experimental data we conclude that the spin-averaged cross-sections are best described in meson-exchange picture. The description of the observed nucleon-nucleus and hyperon-nucleus spin-orbit potentials are found to be consistent with the quark-gluon exchange picture. (author)