Spectra of correlators in the relaxation time approximation of kinetic theory

Abstract The relaxation time approximation (RTA) of the kinetic Boltzmann equation is likely the simplest window into the microscopic properties of collective real-time transport. Within this framework, we analytically compute all retarded two-point Green’s functions of the energy-momentum tensor an...

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Main Authors: Matej Bajec, Sašo Grozdanov, Alexander Soloviev
Format: Article
Language:English
Published: SpringerOpen 2024-08-01
Series:Journal of High Energy Physics
Subjects:
Online Access:https://doi.org/10.1007/JHEP08(2024)065
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author Matej Bajec
Sašo Grozdanov
Alexander Soloviev
author_facet Matej Bajec
Sašo Grozdanov
Alexander Soloviev
author_sort Matej Bajec
collection DOAJ
description Abstract The relaxation time approximation (RTA) of the kinetic Boltzmann equation is likely the simplest window into the microscopic properties of collective real-time transport. Within this framework, we analytically compute all retarded two-point Green’s functions of the energy-momentum tensor and a conserved U(1) current in thermal states with classical massless particles (a ‘CFT’) at non-zero density, and in the absence and presence of broken translational symmetry. This is done in 2 + 1 and 3 + 1 dimensions. RTA allows a full explicit analysis of the analytic structure of different correlators (poles versus branch cuts) and the transport properties that they imply (the thermoelectric conductivities, and the hydrodynamic, quasihydrodynamic and gapped mode dispersion relations). Our inherently weakly coupled analysis thereby also enables a direct comparison with previously known strongly coupled results in holographic CFTs dual to the Einstein-Maxwell-axion theories.
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spelling doaj-art-d95477606ffc4d0abdb83dbff79dbc5b2024-11-24T12:04:57ZengSpringerOpenJournal of High Energy Physics1029-84792024-08-012024813910.1007/JHEP08(2024)065Spectra of correlators in the relaxation time approximation of kinetic theoryMatej Bajec0Sašo Grozdanov1Alexander Soloviev2Faculty of Mathematics and Physics, University of LjubljanaFaculty of Mathematics and Physics, University of LjubljanaFaculty of Mathematics and Physics, University of LjubljanaAbstract The relaxation time approximation (RTA) of the kinetic Boltzmann equation is likely the simplest window into the microscopic properties of collective real-time transport. Within this framework, we analytically compute all retarded two-point Green’s functions of the energy-momentum tensor and a conserved U(1) current in thermal states with classical massless particles (a ‘CFT’) at non-zero density, and in the absence and presence of broken translational symmetry. This is done in 2 + 1 and 3 + 1 dimensions. RTA allows a full explicit analysis of the analytic structure of different correlators (poles versus branch cuts) and the transport properties that they imply (the thermoelectric conductivities, and the hydrodynamic, quasihydrodynamic and gapped mode dispersion relations). Our inherently weakly coupled analysis thereby also enables a direct comparison with previously known strongly coupled results in holographic CFTs dual to the Einstein-Maxwell-axion theories.https://doi.org/10.1007/JHEP08(2024)065Thermal Field TheoryField Theory Hydrodynamics
spellingShingle Matej Bajec
Sašo Grozdanov
Alexander Soloviev
Spectra of correlators in the relaxation time approximation of kinetic theory
Journal of High Energy Physics
Thermal Field Theory
Field Theory Hydrodynamics
title Spectra of correlators in the relaxation time approximation of kinetic theory
title_full Spectra of correlators in the relaxation time approximation of kinetic theory
title_fullStr Spectra of correlators in the relaxation time approximation of kinetic theory
title_full_unstemmed Spectra of correlators in the relaxation time approximation of kinetic theory
title_short Spectra of correlators in the relaxation time approximation of kinetic theory
title_sort spectra of correlators in the relaxation time approximation of kinetic theory
topic Thermal Field Theory
Field Theory Hydrodynamics
url https://doi.org/10.1007/JHEP08(2024)065
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AT sasogrozdanov spectraofcorrelatorsintherelaxationtimeapproximationofkinetictheory
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