On diffractive photoproduction and electroproduction of the psi's

The authors assume the existence of a series of mesons phi /sub cn/ with a cc charmed quark structure and masses m( phi /sub cn/)/sup 2/=m ( phi /sub c/)/sup 2/(1+ alpha /sub c/n), n=0,1,2..., with the 3.1, 3.7, and 4.1 GeV states the first three in the series. Photoproduction and electroproduction experiments will play an important role in the study of these mesons. The authors use generalised vector dominance to estimate the corresponding cross sections for the various phi /sub c /'s in the charm scheme. The results differ considerably from those expected in the colour octet interpretation, so photoproduction experiments will be useful to discriminate the two schemes and provide tests for the various GVD assumptions. (17 refs)