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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todo:paper_05562813_v86_n1_p014907-1_Aad2023-10-03T15:35:06Z Measurement of the azimuthal anisotropy for charged particle production in √S NN = 2.76 TeV lead-lead collisions with the ATLAS detector Aad, G. 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. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_05562813_v86_n1_p014907-1_Aad |
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Universidad de Buenos Aires |
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I-28 |
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R-134 |
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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. |
| format |
JOUR |
| author |
Aad, G. |
| spellingShingle |
Aad, G. Measurement of the azimuthal anisotropy for charged particle production in √S NN = 2.76 TeV lead-lead collisions with the ATLAS detector |
| author_facet |
Aad, G. |
| author_sort |
Aad, G. |
| title |
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 |
| url |
http://hdl.handle.net/20.500.12110/paper_05562813_v86_n1_p014907-1_Aad |
| work_keys_str_mv |
AT aadg measurementoftheazimuthalanisotropyforchargedparticleproductioninsnn276tevleadleadcollisionswiththeatlasdetector |
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