Correlated scalar perturbations and gravitational waves from axion inflation

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Autori principali: Corbà, Sofia P., Sorbo, Lorenzo
Natura: Preprint
Pubblicazione: 2024
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author Corbà, Sofia P.
Sorbo, Lorenzo
author_facet Corbà, Sofia P.
Sorbo, Lorenzo
contents The scalar and tensor fluctuations generated during inflation can be correlated, if arising from the same underlying mechanism. In this paper we investigate such correlation in the model of axion inflation, where the rolling inflaton produces quanta of a $U(1)$ gauge field which, in turn, source scalar and tensor fluctuations. We compute the primordial correlator of the curvature perturbation, $ζ$, with the gravitational energy density, $Ω_{GW}$, at frequencies probed by gravitational wave detectors. This two-point function receives two contributions: one arising from the correlation of gravitational waves with the scalar perturbations generated by the standard mechanism of amplification of vacuum fluctuations, and the other coming from the correlation of gravitational waves with the scalar perturbations sourced by the gauge field. Our analysis shows that the former effect is generally dominant. For typical values of the parameters, the correlator, normalized by the amplitude of $ζ$ and by the fractional energy in gravitational waves at interferometer frequencies, turns out to be of the order of $ 10^{-4}÷10^{-2}$.
format Preprint
id arxiv_https___arxiv_org_abs_2403_03338
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Correlated scalar perturbations and gravitational waves from axion inflation
Corbà, Sofia P.
Sorbo, Lorenzo
Cosmology and Nongalactic Astrophysics
High Energy Physics - Phenomenology
High Energy Physics - Theory
The scalar and tensor fluctuations generated during inflation can be correlated, if arising from the same underlying mechanism. In this paper we investigate such correlation in the model of axion inflation, where the rolling inflaton produces quanta of a $U(1)$ gauge field which, in turn, source scalar and tensor fluctuations. We compute the primordial correlator of the curvature perturbation, $ζ$, with the gravitational energy density, $Ω_{GW}$, at frequencies probed by gravitational wave detectors. This two-point function receives two contributions: one arising from the correlation of gravitational waves with the scalar perturbations generated by the standard mechanism of amplification of vacuum fluctuations, and the other coming from the correlation of gravitational waves with the scalar perturbations sourced by the gauge field. Our analysis shows that the former effect is generally dominant. For typical values of the parameters, the correlator, normalized by the amplitude of $ζ$ and by the fractional energy in gravitational waves at interferometer frequencies, turns out to be of the order of $ 10^{-4}÷10^{-2}$.
title Correlated scalar perturbations and gravitational waves from axion inflation
topic Cosmology and Nongalactic Astrophysics
High Energy Physics - Phenomenology
High Energy Physics - Theory
url https://arxiv.org/abs/2403.03338