Analysis of the apparent nuclear modification in peripheral Pb-Pb collisions at 5.02 TeV

Acharya, S.; Acosta, F. T.; Adamová, Dagmar; Bielčík, J.; Bielčíková, Jana; Broz, M.; Contreras, J. G.; Horák, D.; Křížek, Filip; Kučera, Vít; Kushpil, Svetlana; Lavička, R.; Mareš, Jiří A.; Petráček, V.; Šumbera, Michal; Závada, Petr

doi:https://dx.doi.org/10.1016/j.physletb.2019.04.047

Number of the records: 1

Analysis of the apparent nuclear modification in peripheral Pb-Pb collisions at 5.02 TeV

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SYSNO ASEP	0505689
Document Type	J - Journal Article
R&D Document Type	Journal Article
Subsidiary J	Článek ve WOS
Title	Analysis of the apparent nuclear modification in peripheral Pb-Pb collisions at 5.02 TeV
Author(s)	Acharya, S. (IN) Acosta, F. T. (US) Adamová, Dagmar (UJF-V)_{RID, ORCID, SAI} Bielčík, J. (CZ) Bielčíková, Jana (UJF-V)_{RID, ORCID, SAI} Broz, M. (CZ) Contreras, J. G. (CZ) Horák, D. (CZ) Křížek, Filip (UJF-V)_{RID, ORCID, SAI} Kučera, Vít (UJF-V)_RID Kushpil, Svetlana (UJF-V)_{RID, ORCID, SAI} Lavička, R. (CZ) Mareš, Jiří A. (FZU-D)_{RID, ORCID} Petráček, V. (CZ) Šumbera, Michal (UJF-V)_{RID, ORCID, SAI} Závada, Petr (FZU-D)_{RID, ORCID}
Number of authors	1012
Source Title	Physics Letters. B. - : Elsevier - ISSN 0370-2693 Roč. 793, č. 6 (2019), s. 420-432
Number of pages	13 s.
Publication form	Print - P
Language	eng - English
Country	NL - Netherlands
Keywords	ALICE collaboration ; heavy ion collisions ; transverse momentum
Subject RIV	BG - Nuclear, Atomic and Molecular Physics, Colliders
OECD category	Nuclear physics
Subject RIV - cooperation	Institute of Physics - Elementary Particles and High Energy Physics
R&D Projects	LTT17018 GA MŠMT - Ministry of Education, Youth and Sports (MEYS)
Research Infrastructure	CERN-CZ - 90058 - Fyzikální ústav AV ČR, v. v. i.
Method of publishing	Open access
Institutional support	FZU-D - RVO:68378271 ; UJF-V - RVO:61389005
UT WOS	000470064800063
EID SCOPUS	85065671184
DOI	10.1016/j.physletb.2019.04.047
Annotation	Charged-particle spectra at midrapidity are measured in Pb-Pb collisions at the centre-of-mass energy per nucleon-nucleon pair root s(NN) = 5.02 TeV and presented in centrality classes ranging from most central (0-5%) to most peripheral (95-100%) collisions. Possible medium effects are quantified using the nuclear modification factor (R-AA) by comparing the measured spectra with those from proton-proton collisions, scaled by the number of independent nucleon-nucleon collisions obtained from a Glauber model. At large transverse momenta (8 < p(T) < 20 GeV/c), the average R-AA is found to increase from about 0.15 in 0-5% central to a maximum value of about 0.8 in 75-85% peripheral collisions, beyond which it falls off strongly to below 0.2 for the most peripheral collisions. Furthermore, R-AA initially exhibits a positive slope as a function of p(T) in the 8-20 GeV/c interval, while for collisions beyond the 80% class the slope is negative. To reduce uncertainties related to event selection and normalization, we also provide the ratio of R-AA in adjacent centrality intervals. Our results in peripheral collisions are consistent with a PYTHIA-based model without nuclear modification, demonstrating that biases caused by the event selection and collision geometry can lead to the apparent suppression in peripheral collisions. This explains the unintuitive observation that R-AA is below unity in peripheral Pb-Pb, but equal to unity in minimum-bias p-Pb collisions despite similar charged-particle multiplicities.
Workplace	Nuclear Physics Institute
Contact	Markéta Sommerová, sommerova@ujf.cas.cz, Tel.: 266 173 228
Year of Publishing	2020
Electronic address	https://doi.org/10.1016/j.physletb.2019.04.047

Number of the records: 1