Complete nonrelativistic-QCD prediction for prompt double J/ψ hadroproduction

We perform a complete study of prompt double J/ψ hadroproduction at leading order in the nonrelativistic-QCD factorization framework by including all possible pairings of the c anti c Fock states ¹S₀^[8], ³S₁^[1,8], and ³P_J^[1,8] with J=0,1,2. We find that the ¹S₀^[8] and ³P_J^[8] channels of Jψ and ψ' production and the ³P_J^[1] and ³S₁^[8] channels of χ_cJ production, which have been overlooked so far, greatly dominate at large invariant masses and rapidity separations of the J/ψ pair, and that their inclusion nearly fills the large gap between previous incomplete predictions within the color-singlet model and the recent measurement by the CMS Collaboration at the CERN LHC, leaving room for next-to-leading-order corrections of typical size.