Nuclear $p_\perp$-broadening of Drell-Yan and quarkonium production from SPS to LHC

Abstract

The nuclear $p_\perp$-broadening of Drell-Yan and quarkonium ($J/\psi$, $\Upsilon$) production in $\pi$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 $\hat{q}(x)\propto x^{-\alpha}$ with $\alpha=0.25$-$0.30$. The magnitude of the transport coefficient at $x=10^{-2}$ is $\hat{q}_0=0.051$ GeV$^2$/fm and $\hat{q}_0=0.075$ GeV$^2$/fm, whether $Q\bar{Q}$ 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.