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Measurement of the azimuthal anisotropy for charged particle production in √s_(NN) = 2.76 TeV lead-lead collisions with the ATLAS detector

Aad, G. and Gray, H. M. and Marshall, Z. and Mateos, D. Lopez and Perez, K. (2012) Measurement of the azimuthal anisotropy for charged particle production in √s_(NN) = 2.76 TeV lead-lead collisions with the ATLAS detector. Physical Review C, 86 (1). Art. No. 014907. ISSN 0556-2813. https://resolver.caltech.edu/CaltechAUTHORS:20120904-080452822

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Abstract

Differential measurements of charged particle azimuthal anisotropy are presented for lead-lead collisions at √s_(NN)=2.76 TeV with the ATLAS detector at the LHC, based on an integrated luminosity of approximately 8 μb^(−1). This anisotropy is characterized via a Fourier expansion of the distribution of charged particles in azimuthal angle relative to the reaction plane, with the coefficients v_n denoting the magnitude of the anisotropy. Significant v_2–v_6 values are obtained as a function of transverse momentum (0.5<p_T<20 GeV), pseudorapidity (|η|<2.5), and centrality using an event plane method. The v_n values for n≥3 are found to vary weakly with both η and centrality, and their p_T dependencies are found to follow an approximate scaling relation, v_n^(1/n)(p_T)∝_v^(21/2)(p_T), except in the top 5% most central collisions. A Fourier analysis of the charged particle pair distribution in relative azimuthal angle (Δφ=φ_a−φ_b) is performed to extract the coefficients v_(n,n)=〈cosnΔφ〉. For pairs of charged particles with a large pseudorapidity gap (|Δη=η_a−η_b|>2) and one particle with p_T<3 GeV, the v_(2,2)–v_(6,6) values are found to factorize as v_(n,n)(p_T^a,p_T^b)≈v_n(p_T^a)v_n(p_T^b) in central and midcentral events. Such factorization suggests that these values of v_(2,2)–v_(6,6) are primarily attributable to the response of the created matter to the fluctuations in the geometry of the initial state. A detailed study shows that the v_(1,1)(p_T^a,p_T^b) data are consistent with the combined contributions from a rapidity-even v_1 and global momentum conservation. A two-component fit is used to extract the v_1 contribution. The extracted v_1 is observed to cross zero at p_T≈1.0 GeV, reaches a maximum at 4–5 GeV with a value comparable to that for v_3, and decreases at higher p_T.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1103/PhysRevC.86.014907DOIUNSPECIFIED
http://link.aps.org/doi/10.1103/PhysRevC.86.014907PublisherUNSPECIFIED
http://prc.aps.org/abstract/PRC/v86/i1/e014907PublisherUNSPECIFIED
Additional Information:© 2012 CERN, for the ATLAS Collaboration. Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Received 14 March 2012; published 24 July 2012. We thank CERN for the very successful operation of the LHC, as well as the support staff from our institutions without whom ATLAS could not be operated efficiently. We acknowledge the support of ANPCyT, Argentina; YerPhI, Armenia; ARC, Australia; BMWF, Austria; ANAS, Azerbaijan; SSTC, Belarus; CNPq and FAPESP, Brazil; NSERC, NRC, and CFI, Canada; CERN; CONICYT, Chile; CAS, MOST, and NSFC, China; COLCIENCIAS,Colombia;MSMTCR,MPOCR, and VSC CR, Czech Republic; DNRF, DNSRC, and Lundbeck Foundation, Denmark; ARTEMIS and ERC, European Union; IN2P3-CNRS, CEA-DSM/IRFU, France; GNAS, Georgia; BMBF, DFG, HGF, MPG, and AvH Foundation, Germany; GSRT, Greece; ISF, MINERVA, GIF, DIP, and Benoziyo Center, Israel; INFN, Italy; MEXT and JSPS, Japan; CNRST, Morocco; FOM and NWO, Netherlands; RCN, Norway; MNiSW, Poland; GRICES and FCT, Portugal; MERYS (MECTS), Romania; MES of Russia and ROSATOM, Russian Federation; JINR; MSTD, Serbia; MSSR, Slovakia;ARRSand MVZT, Slovenia; DST/NRF, South Africa; MICINN, Spain; SRC and Wallenberg Foundation, Sweden; SER, SNSF, and Cantons of Bern and Geneva, Switzerland; NSC, Taiwan; TAEK, Turkey; STFC, the Royal Society and Leverhulme Trust, United Kingdom; DOE and NSF, United States of America. The crucial computing support from all WLCG partners is acknowledged gratefully, in particular from CERN and the ATLAS Tier-1 facilities at TRIUMF (Canada), NDGF (Denmark, Norway, Sweden), CC-IN2P3 (France), KIT/GridKA (Germany), INFN-CNAF (Italy), NLT1 (Netherlands), PIC (Spain), ASGC (Taiwan), RAL (UK), and BNL (USA) and in the Tier-2 facilities worldwide.
Funders:
Funding AgencyGrant Number
ANPCyT (Argentina)UNSPECIFIED
YerPhl (Armenia)UNSPECIFIED
ARC (Australia)UNSPECIFIED
BMWF (Austria)UNSPECIFIED
ANAS (Azerbaijan)UNSPECIFIED
SSTC (Belarus)UNSPECIFIED
CNPq and FAPESP (Brazil)UNSPECIFIED
NSERC (Canada)UNSPECIFIED
NRC and CFI (Canada)UNSPECIFIED
CERNUNSPECIFIED
CONICYT (Chile)UNSPECIFIED
CASUNSPECIFIED
MOST and NSFC (China)UNSPECIFIED
COLCIENCIAS (Colombia)UNSPECIFIED
MSMT CR (Czech Republic)UNSPECIFIED
MPO CR and VSC CR (Czech Republic)UNSPECIFIED
DNRF (Denmark)UNSPECIFIED
DNSRC and Lundbeck Foundation (Denmark)UNSPECIFIED
ARTEMIS and ERCUNSPECIFIED
European UnionUNSPECIFIED
IN2P3-CNRS (France)UNSPECIFIED
CEA-DSM/IRFU (France)UNSPECIFIED
GNAS (Georgia)UNSPECIFIED
BMBF (Germany)UNSPECIFIED
DFG (Germany)UNSPECIFIED
HGF (Germany)UNSPECIFIED
MPG and AvH Foundation (Germany)UNSPECIFIED
GSRT (Greece)UNSPECIFIED
ISF (Israel)UNSPECIFIED
MINERVA (Israel)UNSPECIFIED
GIF (Israel)UNSPECIFIED
DIP and Benoziyo Center (Israel)UNSPECIFIED
INFN (Italy)UNSPECIFIED
MEXT and JSPS (Japan)UNSPECIFIED
CNRST (Morocco)UNSPECIFIED
FOM and NWO (The Netherlands)UNSPECIFIED
RCN (Norway)UNSPECIFIED
MNiSW (Poland)UNSPECIFIED
GRICES and FCT (Portugal)UNSPECIFIED
MERYS (MECTS) (Romania)UNSPECIFIED
MES of Russia and ROSATOMUNSPECIFIED
Russian FederationUNSPECIFIED
JINRUNSPECIFIED
MSTD (Serbia)UNSPECIFIED
MSSR (Slovakia)UNSPECIFIED
ARRS and MVZT (Slovenia)UNSPECIFIED
DST/NRF (South Africa)UNSPECIFIED
MICINN (Spain)UNSPECIFIED
SRC and Wallenberg Foundation (Sweden)UNSPECIFIED
SER (Switzerland)UNSPECIFIED
SNSF and Cantons of Bern in Geneva (Switzerland)UNSPECIFIED
NSC (Taiwan)UNSPECIFIED
TAEK (Turkey)UNSPECIFIED
STFC (United Kingdom)UNSPECIFIED
Royal Society and Leverhulme Trust (United Kingdom)UNSPECIFIED
Department of Energy (DOE)UNSPECIFIED
NSFUNSPECIFIED
Issue or Number:1
Classification Code:PACS: 25.75.Dw, 25.75.Ld
Record Number:CaltechAUTHORS:20120904-080452822
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20120904-080452822
Official Citation:Measurement of the azimuthal anisotropy for charged particle production in √sNN=2.76 TeV lead-lead collisions with the ATLAS detector G. Aad et al. (ATLAS Collaboration) Published 24 July 2012 (41 pages) 014907
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:33807
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:04 Sep 2012 15:37
Last Modified:03 Oct 2019 04:13

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