J/ψ+c+(c)over-bar photoproduction in e+e- scattering -: art. no. 014015

We investigate the J/psi+c+(c) over bar photoproduction in e(+)e(-) collision at CERN LEP II energies. The physical motivations for this study are the following: (1) such a process was not considered in previous investigations of J/psi photoproduction in e(+)e(-) interaction, and we show in this work that it is worthwhile to do so in order to make sound predictions for experimental comparison; (2) from recent Belle experiment results, the process with the same final states at the B factory has a theoretically yet unexplainable large fraction; hence it is interesting to see what may happen at other colliders; (3) the process can be measured with a high accuracy at the planned linear colliders; (4) it is necessary to take this process into consideration in elucidating the quarkonium production mechanism, especially in testing the universality of nonrelativistic QCD nonperturbative matrix elements. We find that the process concerned is really important at LEP experimental energies; within the theoretical uncertainties, it is of similar magnitude to the other color-singlet processes when the transverse momentum p(T)>1 GeV. Nevertheless, to explain the recent DELPHI experimental result, the color-octet mechanism is still necessary, but with a shrunken contribution compared to previous analysis. It is found that the J/psi+c+(c) over bar photoproduction process cannot be mimicked by the simple fragmentation scheme.