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

G. Aad; Nele Maria Philomena Boelaert; Mogens Dam; Jørgen Beck Hansen; Peter Henrik Hansen; John Renner Hansen; Jørn Dines Hansen; Simon Johann Franz Heisterkamp; Morten Dam Jørgensen; Esben Bryndt Klinkby; Sascha Mehlhase; Björn Stefan Nilsson; Troels Christian Petersen; Ask Emil Løvschall-Jensen; Stefania Xella

doi:10.1103/PhysRevC.86.014907

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

G. Aad, Nele Maria Philomena Boelaert, Mogens Dam, Jørgen Beck Hansen, Peter Henrik Hansen, John Renner Hansen, Jørn Dines Hansen, Simon Johann Franz Heisterkamp, Morten Dam Jørgensen, Esben Bryndt Klinkby, Sascha Mehlhase, Björn Stefan Nilsson, Troels Christian Petersen, Ask Emil Løvschall-Jensen, Stefania Xella

367 Citations (Scopus)

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 v₂–v₆ 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 v₁ and global momentum conservation.A two-component fit is used to extract the v₁ contribution. The extracted v₁ isobserved to cross zero at p_T ≈ 1.0 GeV, reaches a maximum at 4–5 GeV with a value comparable to that for v₃, and decreases at higher p_T.

Original language	English
Journal	Physical Review C (Nuclear Physics)
Volume	86
Issue number	1
Pages (from-to)	014907
Number of pages	41
ISSN	0556-2813
DOIs	https://doi.org/10.1103/PhysRevC.86.014907
Publication status	Published - 24 Jun 2012

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10.1103/PhysRevC.86.014907

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Aad, G., Boelaert, N. M. P., Dam, M., Hansen, J. B., Hansen, P. H., Hansen, J. R., Hansen, J. D., Heisterkamp, S. J. F., Jørgensen, M. D., Klinkby, E. B., Mehlhase, S., Nilsson, B. S., Petersen, T. C., Løvschall-Jensen, A. E., & Xella, S. (2012). Measurement of the azimuthal anisotropy for charged particle production in vsNN=2.76 TeV lead-lead collisions with the ATLAS detector. Physical Review C (Nuclear Physics), 86(1), 014907. https://doi.org/10.1103/PhysRevC.86.014907

Aad, G, Boelaert, NMP, Dam, M , Hansen, JB , Hansen, PH , Hansen, JR , Hansen, JD, Heisterkamp, SJF, Jørgensen, MD, Klinkby, EB, Mehlhase, S, Nilsson, BS, Petersen, TC, Løvschall-Jensen, AE & Xella, S 2012, 'Measurement of the azimuthal anisotropy for charged particle production in vsNN=2.76 TeV lead-lead collisions with the ATLAS detector', Physical Review C (Nuclear Physics), vol. 86, no. 1, pp. 014907. https://doi.org/10.1103/PhysRevC.86.014907

@article{bd28ae5eaa2b4a99855377fadcf394b0,

title = "Measurement of the azimuthal anisotropy for charged particle production in vsNN=2.76 TeV lead-lead collisions with the ATLAS detector",

abstract = "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/n n (pT) ∝ v1/2 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 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(pa T, pb T) ≈ vn(pa T)vn(pb T) 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(pa T, pb T) 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.",

author = "G. Aad and Boelaert, {Nele Maria Philomena} and Mogens Dam and Hansen, {J{\o}rgen Beck} and Hansen, {Peter Henrik} and Hansen, {John Renner} and Hansen, {J{\o}rn Dines} and Heisterkamp, {Simon Johann Franz} and J{\o}rgensen, {Morten Dam} and Klinkby, {Esben Bryndt} and Sascha Mehlhase and Nilsson, {Bj{\"o}rn Stefan} and Petersen, {Troels Christian} and L{\o}vschall-Jensen, {Ask Emil} and Stefania Xella",

year = "2012",

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doi = "10.1103/PhysRevC.86.014907",

language = "English",

volume = "86",

pages = "014907",

journal = "Physical Review C",

issn = "2469-9985",

publisher = "American Physical Society",

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T1 - Measurement of the azimuthal anisotropy for charged particle production in vsNN=2.76 TeV lead-lead collisions with the ATLAS detector

AU - Aad, G.

AU - Boelaert, Nele Maria Philomena

AU - Dam, Mogens

AU - Hansen, Jørgen Beck

AU - Hansen, Peter Henrik

AU - Hansen, John Renner

AU - Hansen, Jørn Dines

AU - Heisterkamp, Simon Johann Franz

AU - Jørgensen, Morten Dam

AU - Klinkby, Esben Bryndt

AU - Mehlhase, Sascha

AU - Nilsson, Björn Stefan

AU - Petersen, Troels Christian

AU - Løvschall-Jensen, Ask Emil

AU - Xella, Stefania

PY - 2012/6/24

Y1 - 2012/6/24

N2 - 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/n n (pT) ∝ v1/2 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 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(pa T, pb T) ≈ vn(pa T)vn(pb T) 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(pa T, pb T) 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.

AB - 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/n n (pT) ∝ v1/2 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 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(pa T, pb T) ≈ vn(pa T)vn(pb T) 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(pa T, pb T) 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.

U2 - 10.1103/PhysRevC.86.014907

DO - 10.1103/PhysRevC.86.014907

M3 - Journal article

SN - 2469-9985

VL - 86

SP - 014907

JO - Physical Review C

JF - Physical Review C

IS - 1

ER -

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

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