On (dis)agreement between different methods of calculation of the imaginary part of the effective action in expanding space-times

We consider two approaches to calculate imaginary parts of effective actions in expanding space-times. While the first approach uses Bogolyubov coefficients, the second one uses the functional integral or the Feynman propagator. In eternally expanding space-times these two approaches give different...

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Bibliographic Details
Published in:arXiv.org 2024-12
Main Authors: Akhmedov, E T, Belkovich, I A, Diakonov, D V, Kazarnovskii, K A
Format: Article
Language:English
Online Access:Get full text
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Summary:We consider two approaches to calculate imaginary parts of effective actions in expanding space-times. While the first approach uses Bogolyubov coefficients, the second one uses the functional integral or the Feynman propagator. In eternally expanding space-times these two approaches give different answers for the imaginary parts. The origin of the difference can be traced to the presence if the wave-functionals for the initial and final states in the functional integral. We show this explicitly on the example of the expanding Poincare patch of the de Sitter space-time.
ISSN:2331-8422