Charged-particle nuclear modification factors in XeXe collisions at √sNN = 5.02 TeV

The di erential yields of charged particles having pseudorapidity within j j < 1 are measured using xenon-xenon (XeXe) collisions at p sNN = 5:44TeV. The data, corresponding to an integrated luminosity of 3.42 b1, were collected in 2017 by the CMS experiment at the LHC. The yields are reported as functions of collision centrality and transverse momentum, pT, from 0.5 to 100 GeV. A previously reported pT spectrum from proton-proton collisions at p s = 5:02TeV is used for comparison after correcting for the di erence in center-of-mass energy. The nuclear modi cation factors using this reference, R AA, are constructed and compared to previous measurements and theoretical predictions. In head-on collisions, the R AA has a value of 0.17 in the pT range of 6{8 GeV, but increases to approximately 0.7 at 100 GeV. Above 6 GeV, the XeXe data show a notably smaller suppression than previous results for lead-lead (PbPb) collisions at p sNN = 5:02TeV when compared at the same centrality (i.e., the same fraction of total cross section). However, the XeXe suppression is slightly greater than that for PbPb in events having a similar number of participating nucleons