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Doctoral Thesis
DOI
10.11606/T.43.2019.tde-28012019-171710
Document
Author
Full name
André Luiz Moura Britto
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2018
Supervisor
Committee
Frenkel, Josif (President)
Escobar, Bruto Max Pimentel
Francisco, Rafael Rodrigues
Helayël- Neto, José Abdalla
Silva, Adilson Jose da
Title in Portuguese
Generalização do Ansatz de Kadanoff-Baym em teorias quânticas de campos à temperatura finita
Keywords in Portuguese
ansatz de Kadanoff-Baym
função de Green
teoria quântica de campos à temperatura finita.
Abstract in Portuguese
No âmbito da teoria quântica de campos (TQC) foram estudados modelos de quench exatamente solúveis. Nestes modelos, obteve-se uma generalização do ansatz de Kadanoff-Baym que se mantém em todos intervalos de tempo. Algumas hipóteses sobre fenômenos de não-equilíbrio em TQC em temperaturas finitas foram analisadas e estendidas neste contexto. Para tanto, examinamos as funções de Green nesses modelos e os comparamos com os resultados aproximados que são frequentemente usados na literatura. Um dos modelos descreve sistemas de não-equilíbrio do tipo vítreo. Esses sistemas exibem um comportamento que é compatível com o esperado do teorema de flutuação-dissipação. As propriedades básicas foram consistentemente deduzidas e resultados explícitos para a temperatura efetiva e frequências características foram obtidas.
Title in English
Generalization of the Kadanoff-Baym Ansatz in Quantum Field Theory at Finite Temperature.
Keywords in English
Green\'s function
Kadanoff-Baym ansatz
quantum field theory at finite temperature.
Abstract in English
We have studied exactly quenched models in the context of Quantum Field Theory(QFT). In these models, a generalization of the Kadanoff-Baym ansatz was obtained which holds at all times. Some assumptions concerning non-equilibrium phenomena in QFT at finite temperatures were analysed and extended in this framework. To this end, we have examined the Green's functions in these models and compared them with the approximated results which are often used in the literature. One of the models describes non-equilibrium systems of the glassy-kind. Such systems exhibit a behaviour which is compatible with that expected from the fluctuation-dissipation theorem. The basic properties were consistently deduced and explicit results for the effective temperature and characteristic frequencies were obtained.
 
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Publishing Date
2019-01-30
 
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