Rest frame vacua of massive Klein–Gordon fields on spatially flat FLRW spacetimes

Abstract We propose a method of projecting the quantum states from a state space of a given geometry into another state space generated by a different geometry, taking care of the correct normalization which is crucial in interpreting the quantum theory. Thanks to this method we can define on any sp...

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Main Author: Ion I. Cotăescu
Format: Article
Language:English
Published: SpringerOpen 2020-07-01
Series:European Physical Journal C: Particles and Fields
Online Access:http://link.springer.com/article/10.1140/epjc/s10052-020-8170-9
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author Ion I. Cotăescu
author_facet Ion I. Cotăescu
author_sort Ion I. Cotăescu
collection DOAJ
description Abstract We propose a method of projecting the quantum states from a state space of a given geometry into another state space generated by a different geometry, taking care of the correct normalization which is crucial in interpreting the quantum theory. Thanks to this method we can define on any spatially flat FLRW spacetime states in which genuine Minkowskian parameters are measured. We use these Minkowskian states for separating the frequencies in the rest frames of the massive scalar particles defining thus the scalar rest frame vacuum. We show that this vacuum is stable on the de Sitter expanding universe where the energy is conserved. In contrast, on a spatially flat FLRW spacetime with a Milne-type scale factor this vacuum is found to be dynamic, corresponding to a time-dependent rest energy interpreted as an effective mass. This dynamic vacuum gives rise to cosmological particle creation which is significant only in the early Milne-type universe considered here. Some interesting features of this new effect are pointed out in a brief analysis.
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spelling doaj.art-2ad85e46b6e1429b854022170553b3982022-12-21T20:26:20ZengSpringerOpenEuropean Physical Journal C: Particles and Fields1434-60441434-60522020-07-0180711110.1140/epjc/s10052-020-8170-9Rest frame vacua of massive Klein–Gordon fields on spatially flat FLRW spacetimesIon I. Cotăescu0West University of TimişoaraAbstract We propose a method of projecting the quantum states from a state space of a given geometry into another state space generated by a different geometry, taking care of the correct normalization which is crucial in interpreting the quantum theory. Thanks to this method we can define on any spatially flat FLRW spacetime states in which genuine Minkowskian parameters are measured. We use these Minkowskian states for separating the frequencies in the rest frames of the massive scalar particles defining thus the scalar rest frame vacuum. We show that this vacuum is stable on the de Sitter expanding universe where the energy is conserved. In contrast, on a spatially flat FLRW spacetime with a Milne-type scale factor this vacuum is found to be dynamic, corresponding to a time-dependent rest energy interpreted as an effective mass. This dynamic vacuum gives rise to cosmological particle creation which is significant only in the early Milne-type universe considered here. Some interesting features of this new effect are pointed out in a brief analysis.http://link.springer.com/article/10.1140/epjc/s10052-020-8170-9
spellingShingle Ion I. Cotăescu
Rest frame vacua of massive Klein–Gordon fields on spatially flat FLRW spacetimes
European Physical Journal C: Particles and Fields
title Rest frame vacua of massive Klein–Gordon fields on spatially flat FLRW spacetimes
title_full Rest frame vacua of massive Klein–Gordon fields on spatially flat FLRW spacetimes
title_fullStr Rest frame vacua of massive Klein–Gordon fields on spatially flat FLRW spacetimes
title_full_unstemmed Rest frame vacua of massive Klein–Gordon fields on spatially flat FLRW spacetimes
title_short Rest frame vacua of massive Klein–Gordon fields on spatially flat FLRW spacetimes
title_sort rest frame vacua of massive klein gordon fields on spatially flat flrw spacetimes
url http://link.springer.com/article/10.1140/epjc/s10052-020-8170-9
work_keys_str_mv AT ionicotaescu restframevacuaofmassivekleingordonfieldsonspatiallyflatflrwspacetimes