High-pT ψψ production as signals for double-parton scattering at hadron colliders

We present an analysis of the ψψ production from double-parton (DP) scattering and single-parton (SP) scattering in the large pT region via colour-octet gluon fragmentation. We find that at the Tevatron the DP ψψ production is at the edge of the detectability at present, and at the LHC, the DP cross section will dominate over the SP cross section in the lower pT(min) region (i.e. pT(min)<7 GeV). We also conclude that the colour-octet mechanism is of crucial importance to the double J/ψ production at high-energy hadron colliders. (author)