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Nonequilibrium quantum field dynamics from the two-particle-irreducible effective action. / Nathan S Laurie

Swansea University Author: Nathan S Laurie

Abstract

The two-particle-irreducible effective action offers a powerful approach to the study of quantum field dynamics far from equilibrium. Recent and upcoming heavy ion collision experiments motivate the study of such nonequilibrium dynamics in an expanding space-time background. For the O(N) model I der...

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Published: 2008
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
URI: https://cronfa.swan.ac.uk/Record/cronfa42254
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last_indexed 2018-08-03T10:09:40Z
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spelling 2018-08-02T16:24:28.5889881 v2 42254 2018-08-02 Nonequilibrium quantum field dynamics from the two-particle-irreducible effective action. 70940cbd0dbed873236f4aac5d3647f8 NULL Nathan S Laurie Nathan S Laurie true true 2018-08-02 The two-particle-irreducible effective action offers a powerful approach to the study of quantum field dynamics far from equilibrium. Recent and upcoming heavy ion collision experiments motivate the study of such nonequilibrium dynamics in an expanding space-time background. For the O(N) model I derive exact, causal evolution equations for the statistical and spectral functions in a longitudinally expanding system. It is followed by an investigation into how the expansion affects the prospect of the system reaching equilibrium. Results are obtained in 1+1 dimensions at next-to- leading order in loop- and 1/N-expansions of the 2PI effective action. I focus on the evolution of the statistical function from highly nonequilibrium initial conditions, presenting a detailed analysis of early, intermediate and late-time dynamics. It is found that dynamics at very early times is attracted by a nonthermal fixed point of the mean field equations, after which interactions attempt to drive the system to equilibrium. The competition between the interactions and the expansion is eventually won by the expansion, with so-called freeze-out emerging naturally in this description. In order to investigate the convergence of the 2PI-1/N expansion in the 0(N) model, I compare results obtained numerically in 1+1 dimensions at leading, next- to-leading and next-to-next-to-leading order in 1/N. Convergence with increasing N, and also with decreasing coupling are discussed. A comparison is also made in the classical statistical field theory limit, where exact numerical results are available. I focus on early-time dynamics and quasi-particle properties far from equilibrium and observe rapid effective convergence already for moderate values of 1/N or the coupling strength. E-Thesis Theoretical physics.;Quantum physics. 31 12 2008 2008-12-31 COLLEGE NANME Physics COLLEGE CODE Swansea University Doctoral Ph.D 2018-08-02T16:24:28.5889881 2018-08-02T16:24:28.5889881 Faculty of Science and Engineering School of Biosciences, Geography and Physics - Physics Nathan S Laurie NULL 1 0042254-02082018162440.pdf 10797962.pdf 2018-08-02T16:24:40.0870000 Output 6310685 application/pdf E-Thesis true 2018-08-02T16:24:40.0870000 false
title Nonequilibrium quantum field dynamics from the two-particle-irreducible effective action.
spellingShingle Nonequilibrium quantum field dynamics from the two-particle-irreducible effective action.
Nathan S Laurie
title_short Nonequilibrium quantum field dynamics from the two-particle-irreducible effective action.
title_full Nonequilibrium quantum field dynamics from the two-particle-irreducible effective action.
title_fullStr Nonequilibrium quantum field dynamics from the two-particle-irreducible effective action.
title_full_unstemmed Nonequilibrium quantum field dynamics from the two-particle-irreducible effective action.
title_sort Nonequilibrium quantum field dynamics from the two-particle-irreducible effective action.
author_id_str_mv 70940cbd0dbed873236f4aac5d3647f8
author_id_fullname_str_mv 70940cbd0dbed873236f4aac5d3647f8_***_Nathan S Laurie
author Nathan S Laurie
author2 Nathan S Laurie
format E-Thesis
publishDate 2008
institution Swansea University
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Biosciences, Geography and Physics - Physics{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Biosciences, Geography and Physics - Physics
document_store_str 1
active_str 0
description The two-particle-irreducible effective action offers a powerful approach to the study of quantum field dynamics far from equilibrium. Recent and upcoming heavy ion collision experiments motivate the study of such nonequilibrium dynamics in an expanding space-time background. For the O(N) model I derive exact, causal evolution equations for the statistical and spectral functions in a longitudinally expanding system. It is followed by an investigation into how the expansion affects the prospect of the system reaching equilibrium. Results are obtained in 1+1 dimensions at next-to- leading order in loop- and 1/N-expansions of the 2PI effective action. I focus on the evolution of the statistical function from highly nonequilibrium initial conditions, presenting a detailed analysis of early, intermediate and late-time dynamics. It is found that dynamics at very early times is attracted by a nonthermal fixed point of the mean field equations, after which interactions attempt to drive the system to equilibrium. The competition between the interactions and the expansion is eventually won by the expansion, with so-called freeze-out emerging naturally in this description. In order to investigate the convergence of the 2PI-1/N expansion in the 0(N) model, I compare results obtained numerically in 1+1 dimensions at leading, next- to-leading and next-to-next-to-leading order in 1/N. Convergence with increasing N, and also with decreasing coupling are discussed. A comparison is also made in the classical statistical field theory limit, where exact numerical results are available. I focus on early-time dynamics and quasi-particle properties far from equilibrium and observe rapid effective convergence already for moderate values of 1/N or the coupling strength.
published_date 2008-12-31T03:52:36Z
_version_ 1763752601639190528
score 11.013799

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