Measurement of the azimuthal anisotropy for charged particle production in √s[subscript NN]=2.76 TeV lead-lead collisions with the ATLAS detector
Name
Aad-2012-Measurement of the azimuthal anisotropy.pdf
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4.39 MB
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Checksum (MD5)
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Author(s)
Taylor, Frank E.
Date Issued
July 2012
Journal
Physical Review C
Publisher
American Physical Society
Citation
Aad, G. et al. “Measurement of the azimuthal anisotropy for charged particle production in √s[subscript NN]=2.76 TeV lead-lead collisions with the ATLAS detector.” Physical Review C 86.2 (2012). ©2012 CERN, for the ATLAS Collaboration
Version
Final published version
Abstract
Differential measurements of charged particle azimuthal anisotropy are presented for lead-lead collisions at √s[subscript NN]=2.76 TeV with the ATLAS detector at the LHC, based on an integrated luminosity of approximately 8 μb[superscript −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[subscript n] denoting the magnitude of the anisotropy. Significant v[subscript 2]–v[subscript 6] values are obtained as a function of transverse momentum (0.52) and one particle with p[subscript T]<3 GeV, the v[subscript 2,2]–v[subscript 6,6] values are found to factorize as v[subscript n,n](p[subscript T][superscript a],p[subscript T][superscript b])≈v[subscript n](p[subscript T][superscript a])v[subscript n](p[subscript T][superscript b]) in central and midcentral events. Such factorization suggests that these values of v[subscript 2,2]–v[subscript 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[subscript 1,1](p[subscript T][superscript a],p[subscript T][superscript b]) data are consistent with the combined contributions from a rapidity-even v[subscript 1] and global momentum conservation. A two-component fit is used to extract the v[subscript 1] contribution. The extracted v[subscript 1] is observed to cross zero at p[subscript T]≈1.0 GeV, reaches a maximum at 4–5 GeV with a value comparable to that for v[subscript 3], and decreases at higher p[subscript T].
MIT Department
Massachusetts Institute of Technology. Department of Physics
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DOI of Published Version
https://doi.org/10.1103/PhysRevC.86.014907
