Viscosity Information from Relativistic Nuclear Collisions: How Perfect is the Fluid Observed at RHIC?

2007/06/30 by Paul Romatschke, Ulrike Romatschke · 30 citations
Physics and Astronomy · #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ph #hep-th #nucl-th

paper · pdf · doi:10.1103/physrevlett.99.172301

published as Phys.Rev.Lett.99:172301,2007 · 4 pages, 5 figures; v2: matches published version, title changed by journal

openalex publication_date 2007/10/24 · arxiv created 2007/10/26 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

Relativistic viscous hydrodynamic fits to Brookhaven Relativistic Heavy Ion Collider data on the centrality dependence of multiplicity, transverse, and elliptic flow for square root s = 200 GeV Au+Au collisions are presented. For standard (Glauber-type) initial conditions, while data on the integrated elliptic flow coefficient v(2) are consistent with a ratio of viscosity over entropy density up to eta/s approximately 0.16, data on minimum bias v(2) seem to favor a much smaller viscosity over entropy ratio, below the bound from the anti-de Sitter conformal field theory conjecture. Some caveats on this result are discussed.

Citations

• Thermodynamics of nonstationary and transient effects in a relativistic gas
• Nonstationary irreversible thermodynamics: A causal relativistic theory
• Viscosity in Strongly Interacting Quantum Field Theories from Black Hole Physics

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