engleski

Transverse momentum spectra and nuclear modification factors of charged particles in pp, p-Pb and Pb-Pb collisions at the LHC

We report the measured transverse momentum (pT) spectra of primary charged particles from pp, p-Pb and Pb-Pb collisions at a center-of-mass energy √sNN=5.02 TeV in the kinematic range of pT<0.15, 50 GeV/c> and |η|<0.8. A significant improvement of systematic uncertainties motivated the reanalysis of data in pp and Pb- Pb collisions at √sNN=2.76 TeV, as well as in p-Pb collisions at √sNN=5.02 TeV, which is also presented. Spectra from Pb-Pb collisions are presented in nine centrality intervals and are compared to a reference spectrum from pp collisions scaled by the number of binary nucleon-nucleon collisions. For central collisions, the pT spectra are suppressed by more than a factor of 7 around 6–7 GeV/c with a significant reduction in suppression towards higher momenta up to 30 GeV/c. The nuclear modification factor RpPb, constructed from the pp and p-Pb spectra measured at the same collision energy, is consistent with unity above 8 GeV/c. While the spectra in both pp and Pb-Pb collisions are substantially harder at √sNN=5.02 TeV compared to 2.76 TeV, the nuclear modification factors show no significant collision energy dependence. The obtained results should provide further constraints on the parton energy loss calculations to determine the transport properties of the hot and dense QCD matter.

heavy ion: scattering ; transverse momentum: momentum spectrum ; quantum chromodynamics: matter ; parton: energy loss ; momentum: high ; up: momentum ; pp: scattering ; nucleus ; charged particle ; suppression ; energy dependence ; impact parameter ; transport theory ; nucleon nucleon ; CERN LHC Coll ; kinematics ; binary

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