Di-J/psi production at the Tevatron and the LHC
  We briefly review recent results which we have obtained in the study of J/psi-pair production at the Tevatron and the LHC. We claim that the existing data set from CMS and D0 point at a significant double-parton-scattering contribution with an effective cross section smaller than that for jet-related observables. We have also derived simple relations involving feed-down fractions from excited states which can help in disentangling the single from the double scatterings. 
Jean-Philippe Lansberg, Hua-Sheng Shao
hep-ph hep-ex