False and genuine decoherence in the early universe: a local observer and time-averaged observables
Abstract We study quantum decoherence of curvature perturbations at superhorizon scales caused by the gravitational nonlinearities. We show that cubic gravitational couplings, constrained by the spatial diffeomorphism invariance, lead to infrared (IR) and ultraviolet (UV) divergences in the decohere...
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| Format: | Article |
| Language: | English |
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SpringerOpen
2025-07-01
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| Series: | Journal of High Energy Physics |
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| Online Access: | https://doi.org/10.1007/JHEP07(2025)266 |
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| author | Fumiya Sano Junsei Tokuda |
| author_facet | Fumiya Sano Junsei Tokuda |
| author_sort | Fumiya Sano |
| collection | DOAJ |
| description | Abstract We study quantum decoherence of curvature perturbations at superhorizon scales caused by the gravitational nonlinearities. We show that cubic gravitational couplings, constrained by the spatial diffeomorphism invariance, lead to infrared (IR) and ultraviolet (UV) divergences in the decoherence rate at one loop. These divergences arise respectively from deep IR fluctuations, which appear as background modes to a local observer, and from violent zero-point fluctuations in the deep UV. We argue that these divergences are unobservable, as they vanish when proper observables are considered. We consider correlators defined using the geodesic distance for IR divergences and time-averaged correlators for UV divergences. To incorporate these observer’s perspective, we propose to use in effective quantum state, defined in terms of actual observables, as a more appropriate probe of the quantum coherence of the system measured by an observer. We then evaluate the finite decoherence rate induced by superhorizon environment during inflation and in the late universe. |
| format | Article |
| id | doaj-art-e47e307284b04d288ef5c4c9975f5c5c |
| institution | Kabale University |
| issn | 1029-8479 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Journal of High Energy Physics |
| spelling | doaj-art-e47e307284b04d288ef5c4c9975f5c5c2025-08-20T03:42:37ZengSpringerOpenJournal of High Energy Physics1029-84792025-07-012025714610.1007/JHEP07(2025)266False and genuine decoherence in the early universe: a local observer and time-averaged observablesFumiya Sano0Junsei Tokuda1Department of Physics, Institute of Science TokyoDepartment of Physics, McGill UniversityAbstract We study quantum decoherence of curvature perturbations at superhorizon scales caused by the gravitational nonlinearities. We show that cubic gravitational couplings, constrained by the spatial diffeomorphism invariance, lead to infrared (IR) and ultraviolet (UV) divergences in the decoherence rate at one loop. These divergences arise respectively from deep IR fluctuations, which appear as background modes to a local observer, and from violent zero-point fluctuations in the deep UV. We argue that these divergences are unobservable, as they vanish when proper observables are considered. We consider correlators defined using the geodesic distance for IR divergences and time-averaged correlators for UV divergences. To incorporate these observer’s perspective, we propose to use in effective quantum state, defined in terms of actual observables, as a more appropriate probe of the quantum coherence of the system measured by an observer. We then evaluate the finite decoherence rate induced by superhorizon environment during inflation and in the late universe.https://doi.org/10.1007/JHEP07(2025)266de Sitter spaceEarly Universe Particle PhysicsRenormalization and RegularizationQuantum Dissipative Systems |
| spellingShingle | Fumiya Sano Junsei Tokuda False and genuine decoherence in the early universe: a local observer and time-averaged observables Journal of High Energy Physics de Sitter space Early Universe Particle Physics Renormalization and Regularization Quantum Dissipative Systems |
| title | False and genuine decoherence in the early universe: a local observer and time-averaged observables |
| title_full | False and genuine decoherence in the early universe: a local observer and time-averaged observables |
| title_fullStr | False and genuine decoherence in the early universe: a local observer and time-averaged observables |
| title_full_unstemmed | False and genuine decoherence in the early universe: a local observer and time-averaged observables |
| title_short | False and genuine decoherence in the early universe: a local observer and time-averaged observables |
| title_sort | false and genuine decoherence in the early universe a local observer and time averaged observables |
| topic | de Sitter space Early Universe Particle Physics Renormalization and Regularization Quantum Dissipative Systems |
| url | https://doi.org/10.1007/JHEP07(2025)266 |
| work_keys_str_mv | AT fumiyasano falseandgenuinedecoherenceintheearlyuniversealocalobserverandtimeaveragedobservables AT junseitokuda falseandgenuinedecoherenceintheearlyuniversealocalobserverandtimeaveragedobservables |