Charged-hadron production in pp, p+Pb, Pb+Pb, and Xe+Xe collisions at p sNN = 5 TeV with the ATLAS detector at the LHC
Abstract
This paper presents measurements of charged-hadron spectra obtained in pp, p+Pb, and Pb+Pb collisions at p s or p sNN = 5.02TeV, and in Xe+Xe collisions at p sNN = 5.44TeV. The data recorded by the ATLAS detector at the LHC have total integrated luminosities of 25 pb-1, 28 nb-1, 0.50 nb-1, and 3 μb-1, respectively. The nuclear modification factors RpPb and RAA are obtained by comparing the spectra in heavy-ion and pp collisions in a wide range of charged-particle transverse momenta and pseudorapidity.
The nuclear modification factor RpPb shows a moderate enhancement above unity with a maximum at pT 3 GeV; the enhancement is stronger in the Pb-going direction. The nuclear modification factors in both Pb+Pb and Xe+Xe collisions feature a significant, centrality-dependent suppression. They show a similar distinct pT-dependence with a local maximum at pT 2 GeV and a local minimum at pT 7 GeV. This dependence is more distinguishable in more central collisions. No significant ||-dependence is found. A comprehensive comparison with several theoretical predictions is also provided. They typically describe RAA better in central collisions and in the pT range from about 10 to 100 GeV.