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

Publication ,  Journal Article
Aad, G; Abbott, B; Abdallah, J; Abdel Khalek, S; Abdelalim, AA; Abdesselam, A; Abdinov, O; Abi, B; Abolins, M; Abou Zeid, OS; Abramowicz, H ...
Published in: Physical Review C - Nuclear Physics
January 1, 2012

Differential measurements of charged particle azimuthal anisotropy are presented for lead-lead collisions at √sNN = 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 vn denoting the magnitude of the anisotropy. Significant v2–v6 values are obtained as a function of transverse momentum (0.5 < pT < 20 GeV), pseudorapidity (|η| < 2.5), and centrality using an event plane method. The vn values for n ≥ 3 are found to vary weakly with both η and centrality, and their pT dependencies are found to follow an approximate scaling relation, v1/nn (pT) ∝ v1/22 (pT), except in the top 5% most central collisions. A Fourier analysis of the charged particle pair distribution in relative azimuthal angle (Δϕ = ϕa − ϕb) is performed to extract the coefficients vn, n = (cos nΔϕ). For pairs of charged particles with a large pseudorapidity gap (|Δη = ηa − ηb| > 2) and one particle with pT < 3 GeV, the v2,2–v6,6 values are found to factorize as vn, n(paT, pbT) ≈ vn(paT)vn(pbT) in central and midcentral events. Such factorization suggests that these values of v2,2–v6,6 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 v1,1(paT, pbT) data are consistent with the combined contributions from a rapidity-even v1 and global momentum conservation.A two-component fit is used to extract the v1 contribution. The extracted v1 isobserved to cross zero at pT ≈ 1.0 GeV, reaches a maximum at 4–5 GeV with a value comparable to that for v3, and decreases at higher pT.

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Published In

Physical Review C - Nuclear Physics

DOI

EISSN

1089-490X

ISSN

0556-2813

Publication Date

January 1, 2012

Volume

86

Issue

1

Start / End Page

014907-1-014907-41

Related Subject Headings

  • Nuclear & Particles Physics
  • 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics
 

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Aad, G., Abbott, B., Abdallah, J., Abdel Khalek, S., Abdelalim, A. A., Abdesselam, A., … Armbruster, A. J. (2012). Measurement of the azimuthal anisotropy for charged particle production in √SNN = 2.76 TeV lead-lead collisions with the ATLAS detector. Physical Review C - Nuclear Physics, 86(1), 014907-1-014907–014941. https://doi.org/10.1103/PhysRevC.86.014907
Aad, G., B. Abbott, J. Abdallah, S. Abdel Khalek, A. A. Abdelalim, A. Abdesselam, O. Abdinov, et al. “Measurement of the azimuthal anisotropy for charged particle production in √SNN = 2.76 TeV lead-lead collisions with the ATLAS detector.” Physical Review C - Nuclear Physics 86, no. 1 (January 1, 2012): 014907-1-014907–41. https://doi.org/10.1103/PhysRevC.86.014907.
Aad G, Abbott B, Abdallah J, Abdel Khalek S, Abdelalim AA, Abdesselam A, et al. Measurement of the azimuthal anisotropy for charged particle production in √SNN = 2.76 TeV lead-lead collisions with the ATLAS detector. Physical Review C - Nuclear Physics. 2012 Jan 1;86(1):014907-1-014907–41.
Aad, G., et al. “Measurement of the azimuthal anisotropy for charged particle production in √SNN = 2.76 TeV lead-lead collisions with the ATLAS detector.” Physical Review C - Nuclear Physics, vol. 86, no. 1, Jan. 2012, pp. 014907-1-014907–41. Scopus, doi:10.1103/PhysRevC.86.014907.
Aad G, Abbott B, Abdallah J, Abdel Khalek S, Abdelalim AA, Abdesselam A, Abdinov O, Abi B, Abolins M, Abou Zeid OS, Abramowicz H, Abreu H, Acerbi E, Acharya BS, Adamczyk L, Adams DL, Addy TN, Adelman J, Aderholz M, Adomeit S, Adragna P, Adye T, Aefsky S, Aguilar-Saavedra JA, Aharrouche M, Ahlen SP, Ahles F, Ahmad A, Ahsan M, Aielli G, Akdogan T, Åkesson TPA, Akimoto G, Akimov AV, Akiyama A, Alam MS, Alam MA, Albert J, Albrand S, Aleksa M, Aleksandrov IN, Alessandria F, Alexa C, Alexander G, Alexandre G, Alexopoulos T, Alhroob M, Aliev M, Alimonti G, Alison J, Aliyev M, Allbrooke BMM, Allport PP, Allwood-Spiers SE, Almond J, Aloisio A, Alon R, Alonso A, Alvarez Gonzalez B, Alviggi MG, Amako K, Amaral P, Amelung C, Ammosov VV, Amorim A, Amor’Os G, Amram N, Anastopoulos C, Ancu LS, Andari N, Andeen T, Anders CF, Anders G, Anderson KJ, Andreazza A, Andrei V, Andrieux ML, Anduaga XS, Angerami A, Anghinolfi F, Anisenkov A, Anjos N, Annovi A, Antonaki A, Antonelli M, Antonov A, Antos J, Anulli F, Aoun S, Aperio Bella L, Apolle R, Arabidze G, Aracena I, Arai Y, Arce ATH, Arfaoui S, Arguin JF, Arik E, Arik M, Armbruster AJ. Measurement of the azimuthal anisotropy for charged particle production in √SNN = 2.76 TeV lead-lead collisions with the ATLAS detector. Physical Review C - Nuclear Physics. 2012 Jan 1;86(1):014907-1-014907–41.

Published In

Physical Review C - Nuclear Physics

DOI

EISSN

1089-490X

ISSN

0556-2813

Publication Date

January 1, 2012

Volume

86

Issue

1

Start / End Page

014907-1-014907-41

Related Subject Headings

  • Nuclear & Particles Physics
  • 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics