FORM-FACTORS OF SEMILEPTONIC DECAYS OF HEAVY MESONS

Semi-leptonic decays of quarkonia to quarkonia (e.g. B-c --> J/Psi) of fer a unique possibility to investigate the structure of confined syst ems. A QCD sum rule analysis yields a momentum transfer dependence whi ch is much stronger than predicted by vector meson dominance. It is ar gued that this is a typical reflection of the bound state nature and i ts experimental investigation could give important insights into the n ature of bound states in a confining theory.