Abstract :
Double J/ψ production on the order of 20–30 pb has been observed by the NA3 collaboration. These ψψ pairs, measured in or π−N interactions at 150 and 280 GeV/c interactions at 400 GeV/c, carry a large fraction of the projectile momentum, xψψ ≥ 0.6 for the 150 GeV/c beam and ≥ 0.4 at 280 GeV/c. We examine several sources of ψψ pair production within QCD, including O(αs4) ψψ production, leading-twist bb production and decay, abd the materialization of heavy-quark Fock states in the projectile. We estimate the production cross section and the single and double J/ψ momentum and mass distributions for each, comparing the results with the NA3 data, and predict ψψ production in pN interactions at 800 GeV/c, accessible to current fixed-target experiments. We also discuss the observable implications of open heavy meson pair production from the intrinsic heavy quark Fock states.
