Double J/psi-meson Production at LHC and 4c-tetraquark state
  The article is devoted to double J/psi-meson production at LHC. Theoretical predictions for pp -> 2J/psi+X cross section at sqrt{s}=7 TeV for different kinematical restrictions are presented. Special attention is payed to possible contribution of novel particles -- tetraquarks build from four c-quarks. According to presented in our article estimates, it is quietly possible to observe at least one of these state (tensor meson) experimentally. 
A. V. Berezhnoy, A. K. Likhoded, A. V. Luchinsky, A. A. Novoselov
hep-ph