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

We present an analysis of the psi psi production from double-parton (DP) scattering and single-parton (SP) scattering in the large p tau region via colour-octet gluon fragmentation. We find that at the Tevatron the DP psi psi 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 pr(min) region (i.e. pr(min) < 7 GeV). We also conclude that the colour-octet mechanism is of crucial importance to the double J/psi production at high-energy hadron colliders.