How deep is the dip and how tall are the wiggles in inflationary power spectra?

Fuente: arXiv
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Auteurs principaux: Briaud, Vadim, Karam, Alexandros, Koivunen, Niko, Tomberg, Eemeli, Veermäe, Hardi, Vennin, Vincent
Format: Preprint
Publié: 2025
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author Briaud, Vadim
Karam, Alexandros
Koivunen, Niko
Tomberg, Eemeli
Veermäe, Hardi
Vennin, Vincent
author_facet Briaud, Vadim
Karam, Alexandros
Koivunen, Niko
Tomberg, Eemeli
Veermäe, Hardi
Vennin, Vincent
contents We study linear scalar perturbations in single-field models of inflation featuring a non-attractor phase. These models lead to a peak in the curvature power spectrum that may result in the formation of primordial black holes. We develop a transfer-matrix formalism, analogous to the S-matrix program in quantum-field theory, that maps perturbations throughout the transitory phase. At scales smaller than the peak, the power spectrum features damped oscillations, and the duration of the transition sets the scale at which power-law damping switches to exponential damping. At scales larger than the peak, we demonstrate that a dip appears in the power spectrum if and only if the inflaton's velocity does not flip sign. We show that the amplitude at the dip always scales as the inverse square-rooted amplitude of the peak, and comment on the physical consequences of this universal relationship. We also test the robustness of our results with a few toy models and interpret them with an intuitive mechanical analogy.
format Preprint
id arxiv_https___arxiv_org_abs_2501_14681
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle How deep is the dip and how tall are the wiggles in inflationary power spectra?
Briaud, Vadim
Karam, Alexandros
Koivunen, Niko
Tomberg, Eemeli
Veermäe, Hardi
Vennin, Vincent
Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
High Energy Physics - Phenomenology
We study linear scalar perturbations in single-field models of inflation featuring a non-attractor phase. These models lead to a peak in the curvature power spectrum that may result in the formation of primordial black holes. We develop a transfer-matrix formalism, analogous to the S-matrix program in quantum-field theory, that maps perturbations throughout the transitory phase. At scales smaller than the peak, the power spectrum features damped oscillations, and the duration of the transition sets the scale at which power-law damping switches to exponential damping. At scales larger than the peak, we demonstrate that a dip appears in the power spectrum if and only if the inflaton's velocity does not flip sign. We show that the amplitude at the dip always scales as the inverse square-rooted amplitude of the peak, and comment on the physical consequences of this universal relationship. We also test the robustness of our results with a few toy models and interpret them with an intuitive mechanical analogy.
title How deep is the dip and how tall are the wiggles in inflationary power spectra?
topic Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2501.14681