EXCLUSIVE ETA(C) PHOTOPRODUCTION AND ELECTROPRODUCTION AT HERA AS A POSSIBLE PROBE OF THE ODDERON SINGULARITY IN QCD

Theory and phenomenology of the eta(c) photo- and electroproduction is developed from the point of view of probing the odderon singularity i n QCD which corresponds to the three gluon exchange mechanism. This me chanism leads to cross-sections which are independent of W-2 for the e xchange of three non-interacting gluons or exhibit an increase with in creasing W-2 (or 1/x) for the odderon intercept above unity. The eta(c ) electroproduction in the three gluon exchange mechanism is shown to be entirely controlled by the transversely polarised virtual photons. The magnitude of the eta(c) photoproduction cross-section is estimated to be around 100-400 pb. The t-dependence of the differential cross-s ection is also discussed. (C) 1997 Published by Elsevier Science B.V.