Parametric Resonance of Entropy Perturbations in Massless Preheating

Moghaddam, Hossein Bazrafshan; Brandenberger, Robert H.; Cai, Yi-Fu; Ferreira, Elisa G. M.

doi:10.48550/arxiv.1409.1784

Cited by 9 publications

(15 citation statements)

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“…In this paper we consider the post-inflation dynamics while relaxing the assumption of a rigid spacetime, incorporating both the Hubble expansion and the contributions from the coupled metric perturbations. Consistent with earlier studies [35][36][37][38][39][40][41][42][43][44], we find that the coupled metric perturbations can have important effects on the preheating dynamics. In the models we consider here, the metric perturbations have a particularly strong effect on the behavior of the adiabatic modes, dominating their effective mass at early times with an oscillating, tachyonic contribution.…”

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confidence: 92%

Preheating after multifield inflation with nonminimal couplings. III. Dynamical spacetime results

et al. 2018

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This paper concludes our semi-analytic study of preheating in inflationary models comprised of multiple scalar fields coupled nonminimally to gravity. Using the covariant framework of Ref.[1], we extend the rigid-spacetime results of Ref.[2] by considering both the expansion of the universe during preheating, as well as the effect of the coupled metric perturbations on particle production. The adiabatic and isocurvature perturbations are governed by different effective masses that scale differently with the nonminimal couplings and evolve differently in time. The effective mass for the adiabatic modes is dominated by contributions from the coupled metric perturbations immediately after inflation. The metric perturbations contribute an oscillating tachyonic term that enhances an early period of significant particle production for the adiabatic modes, which ceases on a time-scale governed by the nonminimal couplings ξ I . The effective mass of the isocurvature perturbations, on the other hand, is dominated by contributions from the fields' potential and from the curvature of the field-space manifold (in the Einstein frame), the balance between which shifts on a time-scale governed by ξ I . As in Refs.

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confidence: 92%

Preheating after multifield inflation with nonminimal couplings. III. Dynamical spacetime results

et al. 2018

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“…(As indicated in Refs. [1,71,[94][95][96][97][98][99][100][101][102] and further analyzed in Ref. [2], the contributions from the metric perturbations, m 2 3,I , may become significant in certain regions of parameter space when one relaxes the rigid-spacetime approximation.)…”

Section: Evolution Of the Fluctuationsmentioning

confidence: 99%

Preheating after multifield inflation with nonminimal couplings. II. Resonance structure

et al. 2018

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This is the second in a series of papers on preheating in inflationary models comprised of multiple scalar fields coupled nonminimally to gravity. In this paper, we work in the rigid-spacetime approximation and consider field trajectories within the single-field attractor, which is a generic feature of these models. We construct the Floquet charts to find regions of parameter space in which particle production is efficient for both the adiabatic and isocurvature modes, and analyze the resonance structure using analytic and semi-analytic arises from the fields' nonminimal couplings in the Jordan frame, and has no analogue in models with minimal couplings. Quantitatively, the approach to the large-ξ I asymptotic solution for isocurvature modes is slower than in the case of the adiabatic modes.

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“…In these toy models the relevant parameter (λ/g 2 ) will need to be fixed arbitrarily, see e.g. [7,9,20,21]. This is in contrast to the model of this paper.…”

Section: Modelmentioning

confidence: 99%

“…[27] for reviews on cosmic strings and structure formation). A way to address this issue was recently suggested in [20][21][22]: each k mode of the fluctuations lives in an effective background χ ef f ij (k) which is generated by all perturbation modes with smaller wavelengths.…”

Section: Parametric Resonancementioning

confidence: 99%

Preheating in an asymptotically safe quantum field theory

2016

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We consider reheating in a class of asymptotically safe quantum field theories recently studied in [1, 2]. These theories allow for an inflationary phase in the very early universe. Inflation ends with a period of reheating. Since the models contain many scalar fields which are intrinsically coupled to the inflaton there is the possibility of parametric resonance instability in the production of these fields, and the danger that the induced curvature fluctuations will become too large. Here we show that the parametric instability indeed arises, and that hence the energy transfer from the inflaton condensate to fluctuating fields is rapid. Demanding that the curvature fluctuations induced by the parametrically amplified entropy modes do not exceed the upper observational bounds puts a lower bound on the number of fields which the model of Ref. [1, 2] must contain. This bound also depends on the total number of e-foldings of the inflationary phase.

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Parametric Resonance of Entropy Perturbations in Massless Preheating

Cited by 9 publications

References 0 publications

Preheating after multifield inflation with nonminimal couplings. III. Dynamical spacetime results

Preheating after multifield inflation with nonminimal couplings. III. Dynamical spacetime results

Preheating after multifield inflation with nonminimal couplings. II. Resonance structure

Preheating in an asymptotically safe quantum field theory

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