Charged-particle pseudorapidity density at mid-rapidity in p–Pb collisions at √sNN = 8.16 TeV
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The pseudorapidity density of charged particles, dNch/dη , in p–Pb collisions has been measured at a centre-of-mass energy per nucleon–nucleon pair of sNN−−−√ = 8.16 TeV at mid-pseudorapidity for non-single-diffractive events. The results cover 3.6 units of pseudorapidity, |η|<1.8 . The dNch/dη value is 19.1±0.7 at |η|<0.5 . This quantity divided by ⟨Npart⟩ / 2 is 4.73±0.20 , where ⟨Npart⟩ is the average number of participating nucleons, is 9.5% higher than the corresponding value for p–Pb collisions at sNN−−−√ = 5.02 TeV. Measurements are compared with models based on different mechanisms for particle production. All models agree within uncertainties with data in the Pb-going side, while HIJING overestimates, showing a symmetric behaviour, and EPOS underestimates the p-going side of the dNch/dη distribution. Saturation-based models reproduce the distributions well for η>−1.3 . The dNch/dη is also measured for different centrality estimators, based both on the charged-particle multiplicity and on the energy deposited in the Zero-Degree Calorimeters. A study of the implications of the large multiplicity fluctuations due to the small number of participants for systems like p–Pb in the centrality calculation for multiplicity-based estimators is discussed, demonstrating the advantages of determining the centrality with energy deposited near beam rapidity.
CitationAcharya S, Acosta FT, Adamová D, Adhya SP, Adler C, Adolfsson J, Aggarwal MM, Aglieri Rinella G, Agnello M, Ahammed Z, Alme J, Altenkaemper L, Djuvsland Ø, Ersdal MR, Fionda FMC, Nystrand J, Rehman Au, Røhrich D, Tambave GJ, Ullaland K, Wagner B, Yuan S, Zhou Z, Arsene IC, Bätzing P, Dordic O, Lardeux A, Lindal S, Mahmood SM, Malik QW, Richter M, Røed K, Skaali TB, Tveter TS, Wikne JC, Zhao C, Helstrup H, Hetland KF, Kileng B, Nesbø SV, Storetvedt M, Langøy R, Lien JA, Ahmad SF, Ahn SU, Aiola S, Akindinov A, Al-Turany M, Alam SN, De Albuquerque DS, ALICE C. Charged-particle pseudorapidity density at mid-rapidity in p–Pb collisions at √sNN = 8.16 TeV. European Physical Journal C. 2019;79:307.
PublisherSpringer Berlin Heidelberg
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