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

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

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 ${\tau }_{\text{hydro}}$ when the system is well described by relativistic viscous hydrodynamics. The subsequent hydrodynamic evolution becomes essentially independent of the hydrodynamic initialization time ${\tau }_{\text{hydro}}$ as long as ${\tau }_{\text{hydro}}$ is chosen in an appropriate range where both kinetic and hydrodynamic descriptions overlap. We find that for $\sqrt{{s}_{NN}}=2.76\phantom{\rule{0.16em}{0ex}}\phantom{\rule{0.16em}{0ex}}\text{TeV}$ central Pb-Pb collisions, the typical timescale when viscous hydrodynamics with shear viscosity over entropy ratio $\eta /s=0.16$ becomes applicable is ${\tau }_{\text{hydro}}\sim 1\phantom{\rule{0.16em}{0ex}}\mathrm{fm}/c$ after the collision.

{
"_oai": {
"updated": "2021-08-28T13:46:11Z",
"id": "oai:repo.scoap3.org:46422",
"sets": [
"PRC"
]
},
"authors": [
{
"raw_name": "Aleksi Kurkela",
"affiliations": [
{
"country": "CERN",
"value": "Theoretical Physics Department, CERN, Geneva, Switzerland and Faculty of Science and Technology, University of Stavanger, 4036 Stavanger, Norway"
}
],
"surname": "Kurkela",
"given_names": "Aleksi",
"full_name": "Kurkela, Aleksi"
},
{
"raw_name": "Aleksas Mazeliauskas",
"affiliations": [
{
"country": "Germany",
"value": "Institut f\u00fcr Theoretische Physik, Universit\u00e4t Heidelberg, 69120 Heidelberg, Germany and Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, USA"
}
],
"surname": "Mazeliauskas",
"given_names": "Aleksas",
"full_name": "Mazeliauskas, Aleksas"
},
{
"raw_name": "Jean-Fran\u00e7ois Paquet",
"affiliations": [
{
"country": "USA",
"value": "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"
}
],
"surname": "Paquet",
"given_names": "Jean-Fran\u00e7ois",
"full_name": "Paquet, Jean-Fran\u00e7ois"
},
{
"raw_name": "S\u00f6ren Schlichting",
"affiliations": [
{
"country": "Germany",
"value": "Fakult\u00e4t f\u00fcr Physik, Universit\u00e4t Bielefeld, D-33615 Bielefeld, Germany and Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA"
}
],
"surname": "Schlichting",
"given_names": "S\u00f6ren",
"full_name": "Schlichting, S\u00f6ren"
},
{
"raw_name": "Derek Teaney",
"affiliations": [
{
"country": "USA",
"value": "Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, USA"
}
],
"surname": "Teaney",
"given_names": "Derek",
"full_name": "Teaney, Derek"
}
],
"titles": [
{
"source": "APS",
"title": "Effective kinetic description of event-by-event pre-equilibrium dynamics in high-energy heavy-ion collisions"
}
],
"dois": [
{
"value": "10.1103/PhysRevC.99.034910"
}
],
"publication_info": [
{
"journal_volume": "99",
"journal_title": "Physical Review C",
"material": "article",
"journal_issue": "3",
"year": 2019
}
],
"\$schema": "http://repo.scoap3.org/schemas/hep.json",
"acquisition_source": {
"date": "2021-08-25T10:36:27.963447",
"source": "APS",
"method": "APS",
"submission_number": "810b323c058f11ecb53772fd3742099d"
},
"page_nr": [
43
],
{
}
],
{
"statement": "Published by the American Physical Society",
"year": "2019"
}
],
"control_number": "46422",
"record_creation_date": "2019-03-27T15:30:09.265492",
"_files": [
{
"checksum": "md5:2969e88a5ede82f78b53616271cd351f",
"filetype": "pdf",
"bucket": "d6ce90d4-5192-4607-abc5-215630187255",
"version_id": "9eefed23-f8d4-43e1-9ae2-b351a98925b3",
"key": "10.1103/PhysRevC.99.034910.pdf",
"size": 6118825
},
{
"checksum": "md5:02a53d64bc0c72ce6876eaf2392462ee",
"filetype": "xml",
"bucket": "d6ce90d4-5192-4607-abc5-215630187255",
"version_id": "5b952c8d-d708-4c3e-8133-faa485ce0992",
"key": "10.1103/PhysRevC.99.034910.xml",
"size": 925695
}
],
"collections": [
{
"primary": "HEP"
},
{
"primary": "Citeable"
},
{
"primary": "Published"
}
],
"arxiv_eprints": [
{
"categories": [
"hep-ph",
"nucl-th"
],
"value": "1805.00961"
}
],
"abstracts": [
{
"source": "APS",
"value": "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 (\u00e0 la \u201cbottom-up\u201d), 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 $<msub><mi>\u03c4</mi><mtext>hydro</mtext></msub>$ when the system is well described by relativistic viscous hydrodynamics. The subsequent hydrodynamic evolution becomes essentially independent of the hydrodynamic initialization time $<msub><mi>\u03c4</mi><mtext>hydro</mtext></msub>$ as long as $<msub><mi>\u03c4</mi><mtext>hydro</mtext></msub>$ is chosen in an appropriate range where both kinetic and hydrodynamic descriptions overlap. We find that for $<mrow><msqrt><msub><mi>s</mi><mrow><mi>N</mi><mi>N</mi></mrow></msub></msqrt><mo>=</mo><mn>2.76</mn><mspace width=\"0.16em\"></mspace><mspace width=\"0.16em\"></mspace><mtext>TeV</mtext></mrow>$ central Pb-Pb collisions, the typical timescale when viscous hydrodynamics with shear viscosity over entropy ratio $<mrow><mi>\u03b7</mi><mo>/</mo><mi>s</mi><mo>=</mo><mn>0.16</mn></mrow>$ becomes applicable is $<mrow><msub><mi>\u03c4</mi><mtext>hydro</mtext></msub><mo>\u223c</mo><mn>1</mn><mspace width=\"0.16em\"></mspace><mrow><mi>fm</mi><mo>/</mo><mi>c</mi></mrow></mrow>$ after the collision."
}
],
"imprints": [
{
"date": "2019-03-27",
"publisher": "APS"
}
]
}
Published on:
27 March 2019
Publisher:
APS
Published in:
Physical Review C , Volume 99 (2019)
Issue 3
DOI:
https://doi.org/10.1103/PhysRevC.99.034910
arXiv:
1805.00961