Isotropization and Thermalization in Heavy Ion Collisions

Abstract

We argue that isotropization and, consequently, thermalization of the system of gluons and quarks produced in an ultrarelativistic heavy ion collision does not follow from Feynman diagram analysis to any order in the coupling constant. We conclude that the apparent thermalization of quarks and gluons, leading to success of perfect fluid hydrodynamics in describing heavy ion collisions at RHIC, can only be attributed to the non-perturbative QCD effects not captured by Feynman diagrams. We proceed by modeling these non-pertrubative thermalization effects using viscous hydrodynamics. We point out that matching Color Glass Condensate inital conditions with viscous hydrodynamics leads to continuous evolution of all components of energy-momentum tensor and, unlike the case of ideal hydrodynamics, does not give a discontinuity in the longitudinal pressure. An important consequence of such a matching is a relationship between the thermalization time and shear viscosity: we observe that small viscosity leads to short thermalization time.

Includes new results. 8 pages, 1 figure, based on proceedings contributions at "Quark Matter 2005" conference in Budapest, Hungary, August 4-9, 2005 and at the workshop on "Quark-Gluon Plasma Thermalization" in Vienna, Austria, August 10-12, 2005

References in corpus (4)

• Viscosity in Strongly Interacting Quantum Field Theories from Black Hole Physics
• The Abelianization of QCD Plasma Instabilities
• Can Thermalization in Heavy Ion Collisions be Described by QCD Diagrams?
• Thoughts on Non-Perturbative Thermalization and Jet Quenching in Heavy Ion Collisions

Cited by in corpus (10)

• Asymptotic perfect fluid dynamics as a consequence of AdS/CFT
• Multi-particle Production and Thermalization in High-Energy QCD
• Early Time Dynamics in Heavy Ion Collisions from AdS/CFT Correspondence
• Heavy Ion Collisions with Transverse Dynamics from Evolving AdS Geometries
• Anisotropic fluid dynamics in the early stage of relativistic heavy-ion collisions
• Extra dimensions, black holes and fireballs at the LHC
• Early anisotropic hydrodynamics and the RHIC early-thermalization and HBT puzzles
• Long-Range Rapidity Correlations in Heavy Ion Collisions at Strong Coupling from AdS/CFT
• Bremsstrahlung and black hole production from collisions of ultra-boosted particles at non-zero impact parameter
• Transverse hydrodynamics with sudden hadronization -- production of strangeness