Bispectrum from five-dimensional inflation

Abstract It was proposed that five-dimensional (5D) inflation can blow up the size of a compact dimension from the 5D Planck length to the micron size, as required by the dark dimension proposal, relating the weakness of the actual gravitational force to the size of the observable universe. Moreover...

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Main Authors: Ignatios Antoniadis, Auttakit Chatrabhuti, Jules Cunat, Hiroshi Isono
Format: Article
Language:English
Published: SpringerOpen 2025-08-01
Series:Journal of High Energy Physics
Subjects:
Online Access:https://doi.org/10.1007/JHEP08(2025)163
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author Ignatios Antoniadis
Auttakit Chatrabhuti
Jules Cunat
Hiroshi Isono
author_facet Ignatios Antoniadis
Auttakit Chatrabhuti
Jules Cunat
Hiroshi Isono
author_sort Ignatios Antoniadis
collection DOAJ
description Abstract It was proposed that five-dimensional (5D) inflation can blow up the size of a compact dimension from the 5D Planck length to the micron size, as required by the dark dimension proposal, relating the weakness of the actual gravitational force to the size of the observable universe. Moreover, it was shown that 5D inflation can generate the (approximate) flat power spectrum of primordial density fluctuations consistent with present observations. Here we compute the bispectrum of primordial scalar perturbations and show that unlike the power spectrum, it differs from the four-dimensional case at all angular distances, due to the fact that in contrast to global dilatations, invariance under special conformal transformations is not restored at late times. Moreover there is an additional enhancement in the squeezed limit.
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institution Kabale University
issn 1029-8479
language English
publishDate 2025-08-01
publisher SpringerOpen
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series Journal of High Energy Physics
spelling doaj-art-679c3d30013f4d998c3bb4c853bbfadf2025-08-24T11:04:18ZengSpringerOpenJournal of High Energy Physics1029-84792025-08-012025812810.1007/JHEP08(2025)163Bispectrum from five-dimensional inflationIgnatios Antoniadis0Auttakit Chatrabhuti1Jules Cunat2Hiroshi Isono3High Energy Physics Research Unit, Faculty of Science, Chulalongkorn UniversityHigh Energy Physics Research Unit, Faculty of Science, Chulalongkorn UniversityLaboratoire de Physique Théorique et Hautes Energies – LPTHE, Sorbonne Université, CNRSHigh Energy Physics Research Unit, Faculty of Science, Chulalongkorn UniversityAbstract It was proposed that five-dimensional (5D) inflation can blow up the size of a compact dimension from the 5D Planck length to the micron size, as required by the dark dimension proposal, relating the weakness of the actual gravitational force to the size of the observable universe. Moreover, it was shown that 5D inflation can generate the (approximate) flat power spectrum of primordial density fluctuations consistent with present observations. Here we compute the bispectrum of primordial scalar perturbations and show that unlike the power spectrum, it differs from the four-dimensional case at all angular distances, due to the fact that in contrast to global dilatations, invariance under special conformal transformations is not restored at late times. Moreover there is an additional enhancement in the squeezed limit.https://doi.org/10.1007/JHEP08(2025)163Cosmological modelsExtra DimensionsLarge Extra Dimensions
spellingShingle Ignatios Antoniadis
Auttakit Chatrabhuti
Jules Cunat
Hiroshi Isono
Bispectrum from five-dimensional inflation
Journal of High Energy Physics
Cosmological models
Extra Dimensions
Large Extra Dimensions
title Bispectrum from five-dimensional inflation
title_full Bispectrum from five-dimensional inflation
title_fullStr Bispectrum from five-dimensional inflation
title_full_unstemmed Bispectrum from five-dimensional inflation
title_short Bispectrum from five-dimensional inflation
title_sort bispectrum from five dimensional inflation
topic Cosmological models
Extra Dimensions
Large Extra Dimensions
url https://doi.org/10.1007/JHEP08(2025)163
work_keys_str_mv AT ignatiosantoniadis bispectrumfromfivedimensionalinflation
AT auttakitchatrabhuti bispectrumfromfivedimensionalinflation
AT julescunat bispectrumfromfivedimensionalinflation
AT hiroshiisono bispectrumfromfivedimensionalinflation