Measurement of the azimuthal anisotropy for charged particle production in root 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 √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 o...
| Main Authors: | , , , , , , , , , , , , , , , , , , , , , , , , |
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| Format: | Journal article |
| Language: | English |
| Published: |
American Physical Society
2012
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| _version_ | 1797088333628702720 |
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| author | Aad, G Abbott, B Abdallah, J Khalek, SA Abdelalim, A Abdesselam, A Abdinov, O Abi, B Abolins, M AbouZeid, O Abramowicz, H Abreu, H Acerbi, E Acharya, B Adamczyk, L Adams, D Addy, T Adelman, J Aderholz, M Adomeit, S Adragna, P Adye, T Aefsky, S Aguilar-Saavedra, J Aharrouche, M |
| author_facet | Aad, G Abbott, B Abdallah, J Khalek, SA Abdelalim, A Abdesselam, A Abdinov, O Abi, B Abolins, M AbouZeid, O Abramowicz, H Abreu, H Acerbi, E Acharya, B Adamczyk, L Adams, D Addy, T Adelman, J Aderholz, M Adomeit, S Adragna, P Adye, T Aefsky, S Aguilar-Saavedra, J Aharrouche, M |
| author_sort | Aad, G |
| collection | OXFORD |
| description | 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 νn denoting the magnitude of the anisotropy. Significant ν2-ν6 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 νn 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, ν n1/n (pT) ∝ ν 21/2 (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 νn,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 ν2,2-ν6,6 values are found to factorize as νn,n(pTa, pTb) ≈ νn(pTa)νn(pTb) in central and midcentral events. Such factorization suggests that these values of ν2,2-ν6,6 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 ν1,1(pTa, pTb) data are consistent with the combined contributions from a rapidity-even ν1 and global momentum conservation.A two-component fit is used to extract the ν1 contribution. The extracted ν1 isobserved to cross zero at pT ≈ 1.0 GeV, reaches a maximum at 4-5 GeV with a value comparable to that for ν3, and decreases at higher pT. |
| first_indexed | 2024-03-07T02:48:32Z |
| format | Journal article |
| id | oxford-uuid:acdd4cb2-9685-4271-89d9-f7ab8ed2e822 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T02:48:32Z |
| publishDate | 2012 |
| publisher | American Physical Society |
| record_format | dspace |
| spelling | oxford-uuid:acdd4cb2-9685-4271-89d9-f7ab8ed2e8222022-03-27T03:31:49ZMeasurement of the azimuthal anisotropy for charged particle production in root s(NN)=2.76 TeV lead-lead collisions with the ATLAS detectorJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:acdd4cb2-9685-4271-89d9-f7ab8ed2e822EnglishSymplectic Elements at OxfordAmerican Physical Society2012Aad, GAbbott, BAbdallah, JKhalek, SAAbdelalim, AAbdesselam, AAbdinov, OAbi, BAbolins, MAbouZeid, OAbramowicz, HAbreu, HAcerbi, EAcharya, BAdamczyk, LAdams, DAddy, TAdelman, JAderholz, MAdomeit, SAdragna, PAdye, TAefsky, SAguilar-Saavedra, JAharrouche, MDifferential √ 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 νn denoting the magnitude of the anisotropy. Significant ν2-ν6 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 νn 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, ν n1/n (pT) ∝ ν 21/2 (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 νn,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 ν2,2-ν6,6 values are found to factorize as νn,n(pTa, pTb) ≈ νn(pTa)νn(pTb) in central and midcentral events. Such factorization suggests that these values of ν2,2-ν6,6 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 ν1,1(pTa, pTb) data are consistent with the combined contributions from a rapidity-even ν1 and global momentum conservation.A two-component fit is used to extract the ν1 contribution. The extracted ν1 isobserved to cross zero at pT ≈ 1.0 GeV, reaches a maximum at 4-5 GeV with a value comparable to that for ν3, and decreases at higher pT. |
| spellingShingle | Aad, G Abbott, B Abdallah, J Khalek, SA Abdelalim, A Abdesselam, A Abdinov, O Abi, B Abolins, M AbouZeid, O Abramowicz, H Abreu, H Acerbi, E Acharya, B Adamczyk, L Adams, D Addy, T Adelman, J Aderholz, M Adomeit, S Adragna, P Adye, T Aefsky, S Aguilar-Saavedra, J Aharrouche, M Measurement of the azimuthal anisotropy for charged particle production in root s(NN)=2.76 TeV lead-lead collisions with the ATLAS detector |
| title | Measurement of the azimuthal anisotropy for charged particle production in root s(NN)=2.76 TeV lead-lead collisions with the ATLAS detector |
| title_full | Measurement of the azimuthal anisotropy for charged particle production in root s(NN)=2.76 TeV lead-lead collisions with the ATLAS detector |
| title_fullStr | Measurement of the azimuthal anisotropy for charged particle production in root 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 root s(NN)=2.76 TeV lead-lead collisions with the ATLAS detector |
| title_short | Measurement of the azimuthal anisotropy for charged particle production in root s(NN)=2.76 TeV lead-lead collisions with the ATLAS detector |
| title_sort | measurement of the azimuthal anisotropy for charged particle production in root s nn 2 76 tev lead lead collisions with the atlas detector |
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