Principal-component analysis of two-particle azimuthal correlations in PbPb and and pPb collisions at CMS
Name
PhysRevC.96.064902.pdf
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699.98 KB
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Author(s)
Allen, Brandon Leigh
Abercrombie, Daniel Robert
Azzolini, Virginia
Barbieri, Richard Alexander
Baty, Austin Alan
Bi, Ran
Brandt, Stephanie Akemi
Busza, Wit
Cali, Ivan Amos
D'Alfonso, Mariarosaria
Date Issued
December 2017
Journal
Physical Review C
Publisher
American Physical Society
Citation
Sirunyan, A. M., et al. “Principal-Component Analysis of Two-Particle Azimuthal Correlations in PbPb and p Pb Collisions at CMS.” Physical Review C, vol. 96, no. 6, Dec. 2017. ©2017 CERN, for the CMS Collaboration
Version
Final published version
Abstract
For the first time a principle-component analysis is used to separate out different orthogonal modes of the two-particle correlation matrix from heavy ion collisions. The analysis uses data from √s[subscript NN] = 2.76 TeV
PbPb and √s[subscript NN] = 5.02 TeV pPb collisions collected by the CMS experiment at the CERN Large Hadron Collider. Two-particle azimuthal correlations have been extensively used to study hydrodynamic flow in heavy ion collisions. Recently it was shown that the expected factorization of two-particle results into a product of the constituent single-particle anisotropies is broken. The new information provided by these modes may shed light on the breakdown of flow factorization in heavy ion collisions. The first two modes (“leading” and “subleading”) of two-particle correlations are presented for elliptical and triangular anisotropies in PbPb and
pPb collisions as a function of pT over a wide range of event activity. The leading mode is found to be essentially equivalent to the anisotropy harmonic previously extracted from two-particle correlation methods. The subleading mode represents a new experimental observable and is shown to account for a large fraction of the factorization breaking recently observed at high transverse momentum. The principle-component analysis technique was also applied to multiplicity fluctuations. These also show a subleading mode. The connection of these new results to previous studies of factorization is discussed.
MIT Department
Massachusetts Institute of Technology. Department of Physics
Massachusetts Institute of Technology. Laboratory for Nuclear Science
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Creative Commons Attribution 4.0 International License
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DOI of Published Version
https://doi.org/10.1103/PhysRevC.96.064902
