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Analytic approach to non-slow-roll inflation

Gianmassimo Tasinato Orcid Logo

Physical Review D, Volume: 103, Issue: 2

Swansea University Author: Gianmassimo Tasinato Orcid Logo

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DOI (Published version): 10.1103/physrevd.103.023535

Abstract

In order to produce primordial black holes, or to enhance the spectrum of primordial gravitational waves at interferometer scales, cosmological inflation should include brief periods of nonattractor evolution, with departures from slow-roll conditions. To better understand these systems we develop a...

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Published in: Physical Review D
ISSN: 2470-0010 2470-0029
Published: American Physical Society (APS) 2021
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URI: https://cronfa.swan.ac.uk/Record/cronfa57530
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spelling 2021-09-08T15:17:07.7999424 v2 57530 2021-08-05 Analytic approach to non-slow-roll inflation cb754b073d1e4949c5e3db97744d3301 0000-0002-9835-4864 Gianmassimo Tasinato Gianmassimo Tasinato true false 2021-08-05 SPH In order to produce primordial black holes, or to enhance the spectrum of primordial gravitational waves at interferometer scales, cosmological inflation should include brief periods of nonattractor evolution, with departures from slow-roll conditions. To better understand these systems we develop a model independent, analytic approach to study cosmological fluctuations in single field inflationary models with short periods of slow-roll violation. We Taylor expand the equations for fluctuations in a quantity parametrizing the duration of slow-roll violation, and find solutions at leading order in this quantity. The resulting spectrum of perturbations is described by few parameters, and presents a pronounced dip followed by a rapid growth in amplitude, as typically found in numerical as well as analytical studies of similar scenarios. We determine new analytic relations between the position and depth of the dip, and the maximal enhancement of the spectrum toward small scales. For a single epoch of slow-roll violation we confirm previous studies finding that the steepest slope of the spectrum has spectral index ns−1=4. On the other hand, when considering multiple phases of slow-roll violation, the slope of the spectrum is generally enhanced. When two epochs of slow-roll violation occur, the spectral index can reach the value ns−1=8, indicating that the slope of the spectrum has memory of the history of non-slow-roll phases during inflation. Journal Article Physical Review D 103 2 American Physical Society (APS) 2470-0010 2470-0029 26 1 2021 2021-01-26 10.1103/physrevd.103.023535 COLLEGE NANME Physics COLLEGE CODE SPH Swansea University Other Funded by SCOAP3 2021-09-08T15:17:07.7999424 2021-08-05T12:09:46.5512260 Faculty of Science and Engineering School of Biosciences, Geography and Physics - Physics Gianmassimo Tasinato 0000-0002-9835-4864 1 57530__20554__fac62d18f0214dae8a37cd334adfdb9a.pdf 57530.pdf 2021-08-05T12:12:05.1645700 Output 756904 application/pdf Version of Record true Released under the terms of the Creative Commons Attribution 4.0 International license true eng https://creativecommons.org/licenses/by/4.0/
title Analytic approach to non-slow-roll inflation
spellingShingle Analytic approach to non-slow-roll inflation
Gianmassimo Tasinato
title_short Analytic approach to non-slow-roll inflation
title_full Analytic approach to non-slow-roll inflation
title_fullStr Analytic approach to non-slow-roll inflation
title_full_unstemmed Analytic approach to non-slow-roll inflation
title_sort Analytic approach to non-slow-roll inflation
author_id_str_mv cb754b073d1e4949c5e3db97744d3301
author_id_fullname_str_mv cb754b073d1e4949c5e3db97744d3301_***_Gianmassimo Tasinato
author Gianmassimo Tasinato
author2 Gianmassimo Tasinato
format Journal article
container_title Physical Review D
container_volume 103
container_issue 2
publishDate 2021
institution Swansea University
issn 2470-0010
2470-0029
doi_str_mv 10.1103/physrevd.103.023535
publisher American Physical Society (APS)
college_str Faculty of Science and Engineering
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hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Biosciences, Geography and Physics - Physics{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Biosciences, Geography and Physics - Physics
document_store_str 1
active_str 0
description In order to produce primordial black holes, or to enhance the spectrum of primordial gravitational waves at interferometer scales, cosmological inflation should include brief periods of nonattractor evolution, with departures from slow-roll conditions. To better understand these systems we develop a model independent, analytic approach to study cosmological fluctuations in single field inflationary models with short periods of slow-roll violation. We Taylor expand the equations for fluctuations in a quantity parametrizing the duration of slow-roll violation, and find solutions at leading order in this quantity. The resulting spectrum of perturbations is described by few parameters, and presents a pronounced dip followed by a rapid growth in amplitude, as typically found in numerical as well as analytical studies of similar scenarios. We determine new analytic relations between the position and depth of the dip, and the maximal enhancement of the spectrum toward small scales. For a single epoch of slow-roll violation we confirm previous studies finding that the steepest slope of the spectrum has spectral index ns−1=4. On the other hand, when considering multiple phases of slow-roll violation, the slope of the spectrum is generally enhanced. When two epochs of slow-roll violation occur, the spectral index can reach the value ns−1=8, indicating that the slope of the spectrum has memory of the history of non-slow-roll phases during inflation.
published_date 2021-01-26T04:13:20Z
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score 11.016235

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