J/ψ pair production at the Fermilab Tevatron -: art. no. 057504

The double J/psi production in p (p) over bar collisions is reexamined. It is found that the J/psi pair production rate obtained in the color-singlet model, at leading order in alpha(s) and with transverse momentum p(T)>4 GeV, is similar in magnitude to what is derived from the color-octet mechanism. Although the double J/psi production process was proven to be observable with data yet collected at the Fermilab Tevatron detectors, our findings show that the analysis on this process using the accumulated data would be no help in the aim of clarifying the quarkonium production mechanisms, but can give information on the nature of the color-singlet prescription for charmonium production. Nevertheless, with more data to be collected in the future, the evidently different features of J/psi pair production in p(T) distribution in two different schemes enable experimental study to give a decisive conclusion on them.