Analytic approach to non-slow-roll inflation

Tasinato, Gianmassimo

doi:10.1103/physrevd.103.023535

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Analytic approach to non-slow-roll inflation

Gianmassimo Tasinato

Physical Review D, Volume: 103, Issue: 2

Swansea University Author: Gianmassimo Tasinato

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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
Online Access:	Check full text
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 BGPS 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 Biosciences Geography and Physics School COLLEGE CODE BGPS 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_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
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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	2021-01-26T05:04:59Z
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Analytic approach to non-slow-roll inflation

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