Double-quarkonium production at a fixed-target experiment at the LHC (AFTER@LHC)

We present predictions for double-quarkonium production in the kinematical region relevant for the proposed fixed-target experiment using the LHC beams (dubbed as AFTER@LHC). These include all spin-triplet S-wave charmonium and bottomonium pairs, i.e. ψ(n1S)+ψ(n2S), ψ(n1S)+ϒ(m1S) and ϒ(m1S)+ϒ(m2S) with n1,n2=1,2 and m1,m2=1,2,3. We calculate the contributions from double-parton scatterings and single-parton scatterings. With an integrated luminosity of 20 fb−1 to be collected at AFTER@LHC, we find that the yields for double-charmonium production are large enough for differential distribution measurements. We discuss some differential distributions for J/ψ+J/ψ production, which can help to study the physics of double-parton and single-parton scatterings in a new energy range and which might also be sensitive to double intrinsic cc¯ coalescence at large negative Feynman x.