Space-dependent step features:transient breakdown of slow-roll, homogeneity, and isotropy during inflation

Lerner, Rose N. and McDonald, John (2009) Space-dependent step features:transient breakdown of slow-roll, homogeneity, and isotropy during inflation. Physical Review D, 79 (2). ISSN 1550-7998

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Abstract

A step feature in the inflaton potential can model a transient breakdown of slow-roll inflation. Here we generalize the step feature to include space-dependence, allowing it also to model a breakdown of homogeneity and isotropy. The space-dependent inflaton potential generates a classical curvature perturbation mode characterized by the wave number of the step inhomogeneity. For inhomogeneities small compared with the horizon at the step, space-dependence has a small effect on the curvature perturbation. Therefore, the smoothly oscillating quantum power spectrum predicted by the homogeneous step is robust with respect to subhorizon space-dependence. For inhomogeneities equal to or greater than the horizon at the step, the space-dependent classical mode can dominate, producing a curvature perturbation in which modes of wave number determined by the step inhomogeneity are superimposed on the oscillating power spectrum. Generation of a space-dependent step feature may therefore provide a mechanism to introduce primordial anisotropy into the curvature perturbation. Space-dependence also modifies the quantum fluctuations, in particular, via resonancelike features coming from mode coupling to amplified superhorizon modes. However, these effects are small relative to the classical modes.

Item Type: Journal Article
Journal or Publication Title: Physical Review D
Subjects:
Departments: Faculty of Science and Technology > Physics
ID Code: 84281
Deposited By: ep_importer_pure
Deposited On: 25 Jan 2017 09:00
Refereed?: Yes
Published?: Published
Last Modified: 22 Jan 2020 03:24
URI: https://eprints.lancs.ac.uk/id/eprint/84281

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