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Title: Azimuthal anisotropy distributions in high-energy collisions

Abstract

Elliptic flow in ultrarelativistic heavy-ion collisions results from the hydrodynamic response to the spatial anisotropy of the initial density profile. A long-standing problem in the interpretation of flow data is that uncertainties in the initial anisotropy are mingled with uncertainties in the response. We argue that the non-Gaussianity of flow fluctuations in small systems with large fluctuations can be used to disentangle the initial state from the response. We apply this method to recent measurements of anisotropic flow in Pb+Pb and p+Pb collisions at the LHC, assuming linear response to the initial anisotropy. The response coefficient is found to decrease as the system becomes smaller and is consistent with a low value of the ratio of viscosity over entropy of η/s 0.19. Deviations from linear response are studied. While they significantly change the value of the response coefficient they do not change the rate of decrease with centrality. Thus, we argue that the estimate of η/s is robust against non-linear effects.

Authors:
 [1]; ORCiD logo [1];  [2]
  1. CNRS (France)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE, Office of Nuclear Science; USDOE
OSTI Identifier:
1228324
Alternate Identifier(s):
OSTI ID: 1190861
Grant/Contract Number:
AC02-05CH11231; ERC-AD-267258
Resource Type:
Journal Article: Published Article
Journal Name:
Physics Letters. Section B
Additional Journal Information:
Journal Volume: 742; Journal Issue: C; Journal ID: ISSN 0370-2693
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS

Citation Formats

Yan, Li, Ollitrault, Jean-Yves, and Poskanzer, Arthur M. Azimuthal anisotropy distributions in high-energy collisions. United States: N. p., 2015. Web. doi:10.1016/j.physletb.2015.01.039.
Yan, Li, Ollitrault, Jean-Yves, & Poskanzer, Arthur M. Azimuthal anisotropy distributions in high-energy collisions. United States. doi:10.1016/j.physletb.2015.01.039.
Yan, Li, Ollitrault, Jean-Yves, and Poskanzer, Arthur M. Sun . "Azimuthal anisotropy distributions in high-energy collisions". United States. doi:10.1016/j.physletb.2015.01.039.
@article{osti_1228324,
title = {Azimuthal anisotropy distributions in high-energy collisions},
author = {Yan, Li and Ollitrault, Jean-Yves and Poskanzer, Arthur M.},
abstractNote = {Elliptic flow in ultrarelativistic heavy-ion collisions results from the hydrodynamic response to the spatial anisotropy of the initial density profile. A long-standing problem in the interpretation of flow data is that uncertainties in the initial anisotropy are mingled with uncertainties in the response. We argue that the non-Gaussianity of flow fluctuations in small systems with large fluctuations can be used to disentangle the initial state from the response. We apply this method to recent measurements of anisotropic flow in Pb+Pb and p+Pb collisions at the LHC, assuming linear response to the initial anisotropy. The response coefficient is found to decrease as the system becomes smaller and is consistent with a low value of the ratio of viscosity over entropy of η/s 0.19. Deviations from linear response are studied. While they significantly change the value of the response coefficient they do not change the rate of decrease with centrality. Thus, we argue that the estimate of η/s is robust against non-linear effects.},
doi = {10.1016/j.physletb.2015.01.039},
journal = {Physics Letters. Section B},
number = C,
volume = 742,
place = {United States},
year = {Sun Mar 01 00:00:00 EST 2015},
month = {Sun Mar 01 00:00:00 EST 2015}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.physletb.2015.01.039

Citation Metrics:
Cited by: 14 works
Citation information provided by
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