The Fluid Nature of Quark-Gluon Plasma

Abstract

Collisions of heavy nuclei at very high energies offer the exciting possibility of experimentally exploring the phase transformation from hadronic to partonic degrees of freedom which is predicted to occur at several times normal nuclear density and/or for temperatures in excess of $\sim 170$ MeV. Such a state, often referred to as a quark-gluon plasma, is thought to have been the dominant form of matter in the universe in the first few microseconds after the Big Bang. Data from the first five years of heavy ion collisions of Brookhaven National Laboratory's Relativistic Heavy Ion Collider (RHIC) clearly demonstrate that these very high temperatures and densities have been achieved. While there are strong suggestions of the role of quark degrees of freedom in determining the final-state distributions of the produced matter, there is also compelling evidence that the matter does {\em not} behave as a quasi-ideal state of free quarks and gluons. Rather, its behavior is that of a dense fluid with very low kinematic viscosity exhibiting strong hydrodynamic flow and nearly complete absorption of high momentum probes. The current status of the RHIC experimental studies is presented, with a special emphasis on the fluid properties of the created matter, which may in fact be the most perfect fluid ever studied in the laboratory.

12 pages, 5 figures; to appear in Proceedings of the 2007 International Conference on Nuclear Physics; version posted as submitted on 27-Sep-07

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Cited by in corpus (7)

• Dynamical collisional energy loss and transport properties of on- and off-shell heavy quarks in vacuum and in the Quark Gluon Plasma
• Exact solutions of relativistic perfect fluid hydrodynamics for a QCD equation of state
• Away-side asymmetry of jet correlation relative to reaction plane: a sensitive probe for jet in-medium modifications
• Influence of quenched jets on di-hadron correlations
• Acceleration and Energy Loss in N=4 SYM
• Bose-Einstein or HBT correlations in high energy reactions
• Theoretical Perspectives: XLIII Rencontres de Moriond - QCD