Pre-equilibrium evolution effects on heavy-ion collision observables
Abstract
To investigate the importance of pre-equilibrium dynamics on relativistic heavy-ion collision observables, we match a highly nonequilibrium early evolution stage, modeled by free-streaming partons generated from the Monte Carlo Kharzeev-Levin-Nardi (MC-KLN) and Monte Carlo Glauber (MC-Glb) models, to a locally approximately thermalized later evolution stage described by viscous hydrodynamics and study the dependence of final hadronic transverse momentum distributions, in particular their underlying radial and anisotropic flows, on the switching time between these stages. Performing a three-parameter fit of the measured values for the average transverse momenta p⊥ for pions, kaons, and protons, as well as the elliptic and triangular flows of charged hadrons $$v^{ch}_{2,3}$$, with the switching time τs, the specific shear viscosity η/s during the hydrodynamic stage, and the kinetic decoupling temperature Tdec as free parameters, we find that the preferred “thermalization” times τs depend strongly on the model of the initial conditions. MC-KLN initial conditions require an earlier transition to hydrodynamic behavior (at τs ≈ 0.13 fm/c), followed by hydrodynamic evolution with a larger specific shear viscosity η/s ≈ 0.2, than MC-Glb initial conditions, which prefer switching at a later time (τs ≈ 0.6 fm/c) followed by a less viscous hydrodynamic evolution with η/s ≈ 0.16. Finally, these new results including pre-equilibrium evolution are compared to fits without a pre-equilibrium stage where all dynamic evolution before the onset of hydrodynamic behavior is ignored. In each case, the quality of the dynamical descriptions for the optimized parameter sets, as well as the observables which show the strongest constraining power for the thermalization time, are discussed.
- Authors:
-
- The Ohio State Univ., Columbus, OH (United States)
- The Ohio State Univ., Columbus, OH (United States); McGill Univ., Montreal, QC (Canada)
- Publication Date:
- Research Org.:
- The Ohio State Univ., Columbus, OH (United States)
- Sponsoring Org.:
- USDOE Office of Science (SC), Nuclear Physics (NP)
- OSTI Identifier:
- 1604531
- Alternate Identifier(s):
- OSTI ID: 1184056
- Grant/Contract Number:
- SC0004286; SC0004104
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Physical Review C, Nuclear Physics
- Additional Journal Information:
- Journal Volume: 91; Journal Issue: 6; Journal ID: ISSN 0556-2813
- Publisher:
- American Physical Society (APS)
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 73 NUCLEAR PHYSICS AND RADIATION PHYSICS
Citation Formats
Liu, Jia, Shen, Chun, and Heinz, Ulrich. Pre-equilibrium evolution effects on heavy-ion collision observables. United States: N. p., 2015.
Web. doi:10.1103/PhysRevC.91.064906.
Liu, Jia, Shen, Chun, & Heinz, Ulrich. Pre-equilibrium evolution effects on heavy-ion collision observables. United States. https://doi.org/10.1103/PhysRevC.91.064906
Liu, Jia, Shen, Chun, and Heinz, Ulrich. Mon .
"Pre-equilibrium evolution effects on heavy-ion collision observables". United States. https://doi.org/10.1103/PhysRevC.91.064906. https://www.osti.gov/servlets/purl/1604531.
@article{osti_1604531,
title = {Pre-equilibrium evolution effects on heavy-ion collision observables},
author = {Liu, Jia and Shen, Chun and Heinz, Ulrich},
abstractNote = {To investigate the importance of pre-equilibrium dynamics on relativistic heavy-ion collision observables, we match a highly nonequilibrium early evolution stage, modeled by free-streaming partons generated from the Monte Carlo Kharzeev-Levin-Nardi (MC-KLN) and Monte Carlo Glauber (MC-Glb) models, to a locally approximately thermalized later evolution stage described by viscous hydrodynamics and study the dependence of final hadronic transverse momentum distributions, in particular their underlying radial and anisotropic flows, on the switching time between these stages. Performing a three-parameter fit of the measured values for the average transverse momenta p⊥ for pions, kaons, and protons, as well as the elliptic and triangular flows of charged hadrons $v^{ch}_{2,3}$, with the switching time τs, the specific shear viscosity η/s during the hydrodynamic stage, and the kinetic decoupling temperature Tdec as free parameters, we find that the preferred “thermalization” times τs depend strongly on the model of the initial conditions. MC-KLN initial conditions require an earlier transition to hydrodynamic behavior (at τs ≈ 0.13 fm/c), followed by hydrodynamic evolution with a larger specific shear viscosity η/s ≈ 0.2, than MC-Glb initial conditions, which prefer switching at a later time (τs ≈ 0.6 fm/c) followed by a less viscous hydrodynamic evolution with η/s ≈ 0.16. Finally, these new results including pre-equilibrium evolution are compared to fits without a pre-equilibrium stage where all dynamic evolution before the onset of hydrodynamic behavior is ignored. In each case, the quality of the dynamical descriptions for the optimized parameter sets, as well as the observables which show the strongest constraining power for the thermalization time, are discussed.},
doi = {10.1103/PhysRevC.91.064906},
journal = {Physical Review C, Nuclear Physics},
number = 6,
volume = 91,
place = {United States},
year = {Mon Jun 08 00:00:00 EDT 2015},
month = {Mon Jun 08 00:00:00 EDT 2015}
}
Web of Science
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Works referencing / citing this record:
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