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arXiv · 2411.02170

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

E. T. Akhmedov·I. A. Belkovich·D. V. Diakonov·K. A. Kazarnovskii
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Abstract

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.

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E. T. Akhmedov, I. A. Belkovich, D. V. Diakonov, K. A. Kazarnovskii. 2024-11-04. On (dis)agreement between different methods of calculation of the imaginary part of the effective action in expanding space-times. https://doi.org/10.1016/j.physletb.2025.139256

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