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

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...

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Publicado: 2012
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_05562813_v86_n1_p014907-1_Aad
http://hdl.handle.net/20.500.12110/paper_05562813_v86_n1_p014907-1_Aad
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
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spelling paper:paper_05562813_v86_n1_p014907-1_Aad2023-06-08T15:41:58Z Measurement of the azimuthal anisotropy for charged particle production in √S NN = 2.76 TeV lead-lead collisions with the ATLAS detector 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 1/n n (p T ) ∝ v 1/2 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 = (cos nΔϕ). 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 a T , p b T ) ≈ v n (p a T )v n (p b T ) 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 a T , p b T ) 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 isobserved 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 . © 2012 CERN, for the ATLAS Collaboration. 2012 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_05562813_v86_n1_p014907-1_Aad http://hdl.handle.net/20.500.12110/paper_05562813_v86_n1_p014907-1_Aad
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
description 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 1/n n (p T ) ∝ v 1/2 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 = (cos nΔϕ). 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 a T , p b T ) ≈ v n (p a T )v n (p b T ) 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 a T , p b T ) 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 isobserved 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 . © 2012 CERN, for the ATLAS Collaboration.
title Measurement of the azimuthal anisotropy for charged particle production in √S NN = 2.76 TeV lead-lead collisions with the ATLAS detector
spellingShingle Measurement of the azimuthal anisotropy for charged particle production in √S NN = 2.76 TeV lead-lead collisions with the ATLAS detector
title_short Measurement of the azimuthal anisotropy for charged particle production in √S NN = 2.76 TeV lead-lead collisions with the ATLAS detector
title_full Measurement of the azimuthal anisotropy for charged particle production in √S NN = 2.76 TeV lead-lead collisions with the ATLAS detector
title_fullStr Measurement of the azimuthal anisotropy for charged particle production in √S NN = 2.76 TeV lead-lead collisions with the ATLAS detector
title_full_unstemmed Measurement of the azimuthal anisotropy for charged particle production in √S NN = 2.76 TeV lead-lead collisions with the ATLAS detector
title_sort measurement of the azimuthal anisotropy for charged particle production in √s nn = 2.76 tev lead-lead collisions with the atlas detector
publishDate 2012
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_05562813_v86_n1_p014907-1_Aad
http://hdl.handle.net/20.500.12110/paper_05562813_v86_n1_p014907-1_Aad
_version_ 1768541801633808384

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