Measurement of the distributions of event-by-event flow harmonics in lead-lead collisions at √sNN = 2.76 TeV with the ATLAS detector at the LHC
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Heavy ion collisionsHarmonic flowEvent-by-event fluctuationUnfoldingHadron-Hadron scattering
Aad, G., Abajyan, T., Abbott, B. et al. Measurement of the distributions of event-by-event flow harmonics in lead-lead collisions at √sNN = 2.76 TeV with the ATLAS detector at the LHC. J. High Energ. Phys. 2013, 183 (2013). [https://doi.org/10.1007/JHEP11(2013)183]
SponsorshipANPCyT; YerPhI, Armenia; Australian Research Council; BMWF; Austrian Science Fund (FWF); Azerbaijan National Academy of Sciences (ANAS); SSTC, Belarus; National Council for Scientific and Technological Development (CNPq); Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP); Natural Sciences and Engineering Research Council of Canada; National Research Centre (NRC); Canada Foundation for Innovation; CERN; Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT); Chinese Academy of Sciences; MOST; National Natural Science Foundation of China; Departamento Administrativo de Ciencia, Tecnologia e Innovacion Colciencias; Ministry of Education, Youth & Sports - Czech Republic; MPO CR; VSC CR; Czech Republic Government; DNRF; Danish Natural Science Research Council; Lundbeckfonden; EPLANET; European Research Council (ERC); NSRF; European Union (EU); Centre National de la Recherche Scientifique (CNRS); CEA-DSM/IRFU, France; GNSF, Georgia; Federal Ministry of Education & Research (BMBF); German Research Foundation (DFG); HGF; Max Planck Society; Alexander von Humboldt Foundation; Greek Ministry of Development-GSRT; NSRF, Greece; Israel Science Foundation; MINERVA; German-Israeli Foundation for Scientific Research and Development; DIP; Benoziyo Center, Israel; Istituto Nazionale di Fisica Nucleare (INFN); Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) Japan Society for the Promotion of Science; CNRST, Morocco; FOM (The Netherlands); Netherlands Organization for Scientific Research (NWO) Netherlands Government; BRF; RCN, Norway; Ministry of Science and Higher Education, Poland; GRICES; Portuguese Foundation for Science and Technology; MERYS (MECTS), Romania; MES of Russia; Russian Federation; JINR; MSTD, Serbia; MSSR, Slovakia; Slovenian Research Agency - Slovenia; MIZS, Slovenia; DST/NRF, South Africa; Spanish Government; SRC; Wallenberg Foundation, Sweden; SER; Swiss National Science Foundation (SNSF); Cantons of Bern and Geneva, Switzerland; National Science Council of Taiwan; Ministry of Energy & Natural Resources - Turkey; Royal Society and Leverhulme Trust, United Kingdom; United States Department of Energy (DOE); National Science Foundation (NSF); Science & Technology Facilities Council (STFC) ST/K003437/1 GRIDPP ST/J002798/1 PP/E000347/1 ST/H001042/2 ST/K50208X/1 ST/L00335X/1 ST/K003658/1 GRIDPP ST/K001329/1 ATLAS ST/J004928/1 ST/I003517/1 ATLAS ST/M000761/1 PP/E003699/2 ST/J005533/1 ST/I005803/1 GRIDPP ST/H001093/2 ST/J004928/1 ATLAS Upgrade ST/K000195/1 ST/K001337/1 ATLAS ST/L000970/1 ST/M001431/1 ST/K001361/1 LHCb Upgrades ST/J005568/1 ST/I006080/1 ST/K003437/1 ST/K001361/1 ATLAS Upgrades ST/K001361/1 GRIDPP ST/K003496/1 ST/K001361/1 MINOS/MINOS+ ST/K000713/1 ST/J005576/1 ST/J501074/1 ST/M001474/1 ST/L003325/1 ST/K001361/1 ATLAS ST/F007418/1 ST/J004936/1 ST/K00140X/1 ST/K00073X/1 ST/H00095X/2 PP/E000487/1 ST/H001069/2 ST/J004944/1 ST/J005460/1 ST/K001388/1 ST/K003658/1 ST/L00352X/1 ST/L001144/1 ST/K00137X/1 ST/F007337/1 ST/K000659/1 ST/G502320/1 ST/I005811/1 PP/E002757/1 ST/I005803/1 ST/L000970/1 ATLAS Upgrade ST/J500641/1 ST/I000186/1 ST/F00754X/1 ST/K001248/1 ST/H00095X/1 PP/E003087/1 ST/J005541/1 ST/L001004/1 ST/I505756/1 ST/K501840/1 ST/K001361/1 LHCb ST/I003142/1 ST/H001093/1 PP/E003699/1 ST/H001042/1 ST/K001264/1 ATLAS ST/K001337/1 ST/K00140X/1 ATLAS ST/K003496/1 GRIDPP ST/K501840/1 GRIDPP ST/M000664/1; ICREA
The distributions of event-by-event harmonic flow coefficients v n for n = 2- 4 are measured in sNN−−−−√ = 2.76 TeV Pb + Pb collisions using the ATLAS detector at the LHC. The measurements are performed using charged particles with transverse momentum p T > 0.5 GeV and in the pseudorapidity range |η| < 2.5 in a dataset of approximately 7 μb−1 recorded in 2010. The shapes of the v n distributions suggest that the associated flow vectors are described by a two-dimensional Gaussian function in central collisions for v 2 and over most of the measured centrality range for v 3 and v 4. Significant deviations from this function are observed for v 2 in mid-central and peripheral collisions, and a small deviation is observed for v 3 in mid-central collisions. In order to be sensitive to these deviations, it is shown that the commonly used multi-particle cumulants, involving four particles or more, need to be measured with a precision better than a few percent. The v n distributions are also measured independently for charged particles with 0.5 < p T < 1 GeV and p T > 1 GeV. When these distributions are rescaled to the same mean values, the adjusted shapes are found to be nearly the same for these two p T ranges. The v n distributions are compared with the eccentricity distributions from two models for the initial collision geometry: a Glauber model and a model that includes corrections to the initial geometry due to gluon saturation effects. Both models fail to describe the experimental data consistently over most of the measured centrality range.