Effective kinetic description of event-by-event pre-equilibrium dynamics in high-energy heavy-ion collisions

Kurkela, Aleksi (Theoretical Physics Department, CERN, Geneva, Switzerland and Faculty of Science and Technology, University of Stavanger, 4036 Stavanger, Norway) ; Mazeliauskas, Aleksas (Institut für Theoretische Physik, Universität Heidelberg, 69120 Heidelberg, Germany and Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, USA) ; Paquet, Jean-François (Department of Physics, Duke University, Durham, North Carolina 27708, USA and Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, USA) ; Schlichting, Sören (Fakultät für Physik, Universität Bielefeld, D-33615 Bielefeld, Germany and Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA) ; Teaney, Derek (Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, USA)

27 March 2019

Abstract: We develop a macroscopic description of the space-time evolution of the energy-momentum tensor during the pre-equilibrium stage of a high-energy heavy-ion collision. Based on a weak coupling effective kinetic description of the microscopic equilibration process (à la “bottom-up”), we calculate the nonequilibrium evolution of the local background energy-momentum tensor as well as the nonequilibrium linear response to transverse energy and momentum perturbations for realistic boost-invariant initial conditions for heavy-ion collisions. We demonstrate how this framework can be used on an event-by-event basis to propagate the energy-momentum tensor from far-from-equilibrium initial-state models to the time τhydro when the system is well described by relativistic viscous hydrodynamics. The subsequent hydrodynamic evolution becomes essentially independent of the hydrodynamic initialization time τhydro as long as τhydro is chosen in an appropriate range where both kinetic and hydrodynamic descriptions overlap. We find that for sNN=2.76TeV central Pb-Pb collisions, the typical timescale when viscous hydrodynamics with shear viscosity over entropy ratio η/s=0.16 becomes applicable is τhydro1fm/c after the collision.


Published in: Physical Review C 99 (2019)
Published by: APS
DOI: 10.1103/PhysRevC.99.034910
arXiv: 1805.00961
License: CC-BY-4.0



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