On the Imaginary Part of the Effective Action in de Sitter Spacetime with Different Regularization Schemes

Fuente: arXiv
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Main Authors: Zhou, Yu, Zhang, Hai-Qing
Format: Preprint
Published: 2025
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author Zhou, Yu
Zhang, Hai-Qing
author_facet Zhou, Yu
Zhang, Hai-Qing
contents The imaginary part of the effective action encodes vacuum instability and particle production in the background field. Two standard approaches are commonly used to derive it: the Bogoliubov method and the Green's function method, which are usually expected to agree. However, in de Sitter spacetime they yield different results. We revisit this problem by introducing explicit time and momentum cutoffs in the Green's function representation of the effective action. The apparent discrepancy is found to be due to the different limiting procedures in regularization, which reproduces the Bogoliubov result and the Green's function result respectively. Therefore, the two approaches are understood to be different regularization limits of the same expression, which clarifies the origin of their disagreement.
format Preprint
id arxiv_https___arxiv_org_abs_2510_13712
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On the Imaginary Part of the Effective Action in de Sitter Spacetime with Different Regularization Schemes
Zhou, Yu
Zhang, Hai-Qing
High Energy Physics - Theory
General Relativity and Quantum Cosmology
The imaginary part of the effective action encodes vacuum instability and particle production in the background field. Two standard approaches are commonly used to derive it: the Bogoliubov method and the Green's function method, which are usually expected to agree. However, in de Sitter spacetime they yield different results. We revisit this problem by introducing explicit time and momentum cutoffs in the Green's function representation of the effective action. The apparent discrepancy is found to be due to the different limiting procedures in regularization, which reproduces the Bogoliubov result and the Green's function result respectively. Therefore, the two approaches are understood to be different regularization limits of the same expression, which clarifies the origin of their disagreement.
title On the Imaginary Part of the Effective Action in de Sitter Spacetime with Different Regularization Schemes
topic High Energy Physics - Theory
General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2510.13712