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Title: Multiplicity scaling in ideal and viscous hydrodynamics

Abstract

Using numerical results from ideal and viscous relativistic hydrodynamic simulations with three different equations of state, for Au+Au and Cu+Cu collisions at different centralities and initial energy densities, we explore the dependence of the eccentricity-scaled elliptic flow, v{sub 2}/{epsilon}, and the produced entropy fraction, {delta}S/S{sub 0}, on the final charged hadron multiplicity density dN{sub ch}/dy per unit transverse overlap area S,(1/S)dN{sub ch}/dy. The viscous hydrodynamic simulations are performed with two different versions of the Israel-Stewart kinetic evolution equations, and in each case we investigate the dependence of the physical observables on the kinetic relaxation time. We find approximate scaling of v{sub 2}/{epsilon} and {delta}S/S{sub 0} with (1/S)dN{sub ch}/dy, with scaling functions that depend on the EOS and, in particular, on the value of the specific shear viscosity {eta}/s. Small scaling violations are seen even in ideal hydrodynamics, caused by a breaking of the scale invariance of ideal fluid dynamics by the freeze-out condition. Viscous hydrodynamics shows somewhat larger scale-breaking effects that increase with increasing {eta}/s and decreasing system size and initial energy density. We propose to use precision studies of these scaling violations to help constrain the shear viscosity {eta}/s of the quark-gluon plasma created in relativistic heavy ion collisions.

Authors:
 [1];  [1]
  1. Department of Physics, Ohio State University, Columbus, OH 43210 (United States)
Publication Date:
OSTI Identifier:
21192127
Resource Type:
Journal Article
Journal Name:
Physical Review. C, Nuclear Physics
Additional Journal Information:
Journal Volume: 78; Journal Issue: 2; Other Information: DOI: 10.1103/PhysRevC.78.024902; (c) 2008 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0556-2813
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ATOM-ATOM COLLISIONS; COPPER; DENSITY; ENERGY DENSITY; ENTROPY; EQUATIONS OF STATE; FREEZING OUT; GOLD; HADRONS; HEAVY ION REACTIONS; HYDRODYNAMICS; IDEAL FLOW; MULTIPLICITY; QUARK MATTER; RELATIVISTIC RANGE; RELAXATION TIME; SCALE INVARIANCE; SCALING; SIMULATION; VISCOSITY

Citation Formats

Huichao, Song, Heinz, Ulrich, and CERN, Physics Department, Theory Division, CH-1211 Geneva 23. Multiplicity scaling in ideal and viscous hydrodynamics. United States: N. p., 2008. Web. doi:10.1103/PHYSREVC.78.024902.
Huichao, Song, Heinz, Ulrich, & CERN, Physics Department, Theory Division, CH-1211 Geneva 23. Multiplicity scaling in ideal and viscous hydrodynamics. United States. doi:10.1103/PHYSREVC.78.024902.
Huichao, Song, Heinz, Ulrich, and CERN, Physics Department, Theory Division, CH-1211 Geneva 23. Fri . "Multiplicity scaling in ideal and viscous hydrodynamics". United States. doi:10.1103/PHYSREVC.78.024902.
@article{osti_21192127,
title = {Multiplicity scaling in ideal and viscous hydrodynamics},
author = {Huichao, Song and Heinz, Ulrich and CERN, Physics Department, Theory Division, CH-1211 Geneva 23},
abstractNote = {Using numerical results from ideal and viscous relativistic hydrodynamic simulations with three different equations of state, for Au+Au and Cu+Cu collisions at different centralities and initial energy densities, we explore the dependence of the eccentricity-scaled elliptic flow, v{sub 2}/{epsilon}, and the produced entropy fraction, {delta}S/S{sub 0}, on the final charged hadron multiplicity density dN{sub ch}/dy per unit transverse overlap area S,(1/S)dN{sub ch}/dy. The viscous hydrodynamic simulations are performed with two different versions of the Israel-Stewart kinetic evolution equations, and in each case we investigate the dependence of the physical observables on the kinetic relaxation time. We find approximate scaling of v{sub 2}/{epsilon} and {delta}S/S{sub 0} with (1/S)dN{sub ch}/dy, with scaling functions that depend on the EOS and, in particular, on the value of the specific shear viscosity {eta}/s. Small scaling violations are seen even in ideal hydrodynamics, caused by a breaking of the scale invariance of ideal fluid dynamics by the freeze-out condition. Viscous hydrodynamics shows somewhat larger scale-breaking effects that increase with increasing {eta}/s and decreasing system size and initial energy density. We propose to use precision studies of these scaling violations to help constrain the shear viscosity {eta}/s of the quark-gluon plasma created in relativistic heavy ion collisions.},
doi = {10.1103/PHYSREVC.78.024902},
journal = {Physical Review. C, Nuclear Physics},
issn = {0556-2813},
number = 2,
volume = 78,
place = {United States},
year = {2008},
month = {8}
}