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Updated: Jun 1, 2026

Setting Limits on Supersymmetry Using Simplified Models
Published on: November 15, 2013
200 A GeV Au + Au collisions serve a nearly perfect quark-gluon liquid
Huichao Song1, Steffen A Bass, Ulrich Heinz
1Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Abstract:
A new robust method to extract the specific shear viscosity (η/s)(QGP) of a quark-gluon plasma (QGP) at temperatures T(c) < T ≲ 2T(c) from the centrality dependence of the eccentricity-scaled elliptic flow v2/ε measured in ultrarelativistic heavy-ion collisions is presented. Coupling viscous fluid dynamics for the QGP with a microscopic transport model for hadronic freeze-out we find for 200 A GeV Au + Au collisions that v2/ε is a universal function of multiplicity density (1/S)(dN(ch)/dy) that depends only on the viscosity but not on the model used for computing the initial fireball eccentricity ε. Comparing with measurements we find 1<4π(η/s)(QGP) < 2.5 where the uncertainty range is dominated by model uncertainties for the values of ε used to normalize the measured v2.
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