Underlying-event properties in pp and p–Pb collisions at √sNN = 5.02 TeV


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Acharya S., Adamová D., Adler A., Aglieri Rinella G., Agnello M., Agrawal N., ...More

Journal of High Energy Physics, vol.2023, no.6, 2023 (SCI-Expanded, Scopus) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 2023 Issue: 6
  • Publication Date: 2023
  • Doi Number: 10.1007/jhep06(2023)023
  • Journal Name: Journal of High Energy Physics
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, INSPEC, zbMATH, Directory of Open Access Journals
  • Keywords: Properties of Hadrons, Quark-Gluon Plasma
  • Open Archive Collection: AVESIS Open Access Collection
  • Yıldız Technical University Affiliated: Yes

Abstract

We report about the properties of the underlying event measured with ALICE at the LHC in pp and p–Pb collisions at sNN = 5.02 TeV. The event activity, quantified by charged-particle number and summed-p T densities, is measured as a function of the leading-particle transverse momentum (pTtrig) . These quantities are studied in three azimuthal-angle regions relative to the leading particle in the event: toward, away, and transverse. Results are presented for three different p T thresholds (0.15, 0.5 and 1 GeV/c) at mid-pseudorapidity (|η| < 0.8). The event activity in the transverse region, which is the most sensitive to the underlying event, exhibits similar behaviour in both pp and p–Pb collisions, namely, a steep increase with pTtrig for low pTtrig , followed by a saturation at pTtrig≈5 GeV/c. The results from pp collisions are compared with existing measurements at other centre-of-mass energies. The quantities in the toward and away regions are also analyzed after the subtraction of the contribution measured in the transverse region. The remaining jet-like particle densities are consistent in pp and p–Pb collisions for pTtrig>10 GeV/c, whereas for lower pTtrig values the event activity is slightly higher in p–Pb than in pp collisions. The measurements are compared with predictions from the PYTHIA 8 and EPOS LHC Monte Carlo event generators. [Figure not available: see fulltext.].