Double prompt J/ψ hadroproduction in the parton Reggeization approach with high-energy resummation

We study double prompt J/ψ hadroproduction within the nonrelativistic-QCD factorization formalism adopting the parton Reggeization approach to treat initial-state radiation in a gauge invariant and infrared-safe way. We present first predictions for the cross section distributions in the transverse momenta of the subleading J/ψ meson and the J/ψ pair. Already at leading order in α${}_s$, these predictions as well as those for the total cross section and its distributions in the invariant mass m${}_{\Psi \Psi }$ and the rapidity separation |Y| of the J/ψ pair nicely agree with recent ATLAS and CMS measurements, except for the large-m${}_{\Psi \Psi }$ and large-|Y| regions, where the predictions substantially undershoot the data. In the latter regions, BFKL resummation is shown to enhance the cross sections by up to a factor of two and so to improve the description of the data.