Photoproduction of charmonia and total charmonium-proton cross sections - art. no. 094022

Elastic virtual photoproduction cross sections gamma *p-->J/psi>(*) over ba r *(psi')p and total charmonium-nucleon cross sections for J/psi, psi', and chi states are calculated in a parameter-free way with the light-cone dipo le formalism and the same input: factorization in impact parameters, light- cone wave functions for the gamma* and the charmonia, and the universal phe nomenological dipole cross section which is fitted to other data. The charm onium wave functions are calculated with four known realistic potentials, a nd two models for the dipole cross section are tested. Very good agreement with data for the cross section of charmonium photoproduction is found in a wide range of s and Q(2). The inclusion of the Melosh spin rotation increa ses the psi' photoproduction rate by a factor of 2-3 and removes previously observed discrepancies in the psi' to J/psi ratio in photoproduction. We a lso calculate the charmonium-proton cross sections whose absolute values an d energy dependences are found to correlate strongly with the sizes of the states.