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Updated: Jul 10, 2026

Dielectric RheoSANS — Simultaneous Interrogation of Impedance, Rheology and Small Angle Neutron Scattering of Complex Fluids
Published on: April 10, 2017
Viscosity information from relativistic nuclear collisions: how perfect is the fluid observed at RHIC?
Paul Romatschke1, Ulrike Romatschke
1Institute for Nuclear Theory, University of Washington, Box 351550, Seattle, Washington 98195, USA.
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.
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