Nuclear p ⊥ -broadening of Drell-Yan and quarkonium production from SPS to LHC

The nuclear p ⊥ -broadening of Drell-Yan and quarkonium ( J/ψ , Υ) production in π A and pA collisions is investigated. The world data follow a simple scaling from SPS to LHC energies, once the process-dependent color factors are properly taken into account, which allows for the extraction of the transport coefficient in cold nuclear matter. We find that q̂(x)∝x^-α with α = 0 . 25–0 . 30. The magnitude of the transport coefficient at x = 10 − 2 is q̂_0=0.051 GeV^2/fm and q̂_0=0.075 GeV^2/fm q ˆ0 = 0 . 075 GeV 2 /fm, whether QQ pairs are assumed to be produced as color octet or color singlet states, respectively. The relation between nuclear broadening data and the (CT14) gluon density is also investigated.