The pseudorapidity density of charged particles with minimum transverse momentum ($p_{\rm T}$) thresholds of 0.15, 0.5, 1, and 2 GeV$/c$ was measured in pp collisions at centre-of-mass energies of $\sqrt{s} = 5.02$ and $13$ TeV with the ALICE detector. The study is carried out for inelastic collisions with at least one primary charged particle having a pseudorapidity ($\eta$) within $\pm0.8$ and $p_{\rm T}$ larger than the corresponding threshold. The measurements were also performed for inelastic and non-single-diffractive events as well as for inelastic events with at least one charged particle having $|\eta|<~1$ in pp collisions at $\sqrt{s} = 5.02$ TeV for the first time at the LHC. The measurements are compared to the PYTHIA 6, PYTHIA 8, and EPOS-LHC models. In general, the models describe the pseudorapidity dependence of particle production well, however, discrepancies are observed for event classes including diffractive events and for the highest transverse momentum threshold ($p_{\rm T} > 2$ GeV$/c$), highlighting the importance of such measurements for tuning event generators. The new measurements agree within uncertainties with results from the ATLAS and CMS experiments.
Submitted to: PRD
e-Print: arXiv:2211.15364 | PDF | inSPIRE
CERN-EP-2022-262
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