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

作者：Acharya, S.; Adamova, D.; Adler, A.; Rinella, G. Aglieri; Agnello, M.; Agrawal, N.; Ahammed, Z.; Ahmad, S.; Ahn, S. U.; Ahuja, I.; Akindinov, A.; Al-Turany, M.; Aleksandrov, D.; Alessandro, B.; Alfanda, H. M.; Alfaro Molina, R.; Ali, B.; Ali, Y.; Alici, A.; Alizadehvandchali, N.; Alkin, A.; Alme, J.; Alocco, G.; Alt, T.; Altsybeev, I.; Anaam, M. N.; Andrei, C.; Andronic, A.; Anguelov, V.; Antinori, F.; Antonioli, P.; Anuj, C.; Apadula, N.; Aphecetche, L.; Appelshaeuser, H.; Arcelli, S.

来源：JOURNAL OF HIGH ENERGY PHYSICS, 2023, (6): 23.

DOI：10.1007/JHEP06(2023)023

• Properties of Hadrons
• Quark-Gluon Plasma

We report about the properties of the underlying event measured with ALICE at the LHC in pp and p-Pb collisions at root sNN = 5.02 TeV. The event activity, quantified by charged-particle number and summed- pT densities, is measured as a function of the leadingparticle transverse momentum (p(T)(trig)). These quantities are studied in three azimuthalangle 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 midpseudorapidity (|eta| < 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 p(T)(trig) for low p(trig) (T), followed by a saturation at p(T)(trig) approximate to 5 GeV/c. The results from pp collisions are compared with existing measurements at other centre-ofmass 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 p(trig) (T) > 10 GeV/c, whereas for lower p(T)(trig) 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.