THE INTERPRETATION OF RAPIDITY GAPS AT HERA

In leading twist deep inelastic ep scattering, the virtual photon inte raction is fast compared to the time scale of soft color rearrangement . We compare the Pomeron exchange model, in which a neutral cluster is preformed, with a gluon exchange model, in which color is exchanged a fter the hard interaction. We find several features of the DIS data an d of data on exclusive hard processes that favor a gluon exchange scen ario. If correct, the postulate of soft color interactions between the produced (<q(q)over bar>) system and the target has important implica tions for other processes. In particular, this may explain the puzzles of charmonium hadroproduction.