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Nonperturbative quantum dynamics of a new inflation model

D Boyanovsky, D Cormier, H. de Vega, R Holman, Prem Kumar Orcid Logo

Physical Review D, Volume: 57, Issue: 4, Pages: 2166 - 2185

Swansea University Author: Prem Kumar Orcid Logo

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DOI (Published version): 10.1103/PhysRevD.57.2166

Abstract

We consider an O(N) model coupled self-consistently to gravity in the semi- classical approximation, where the field is subject to ‘new inflation’ type initial conditions. We study the dynamics self-consistently and non-perturbatively with non-equilibrium field theory methods in the large N limit. W...

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Published in: Physical Review D
Published: 1998
URI: https://cronfa.swan.ac.uk/Record/cronfa16120
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Abstract: We consider an O(N) model coupled self-consistently to gravity in the semi- classical approximation, where the field is subject to ‘new inflation’ type initial conditions. We study the dynamics self-consistently and non-perturbatively with non-equilibrium field theory methods in the large N limit. We find that spinodal instabilities drive the growth of non-perturbatively large quantum fluctuations which shut off the inflationary growth of the scale factor. We find that a very specific combination of these large fluctuations plus the in- flaton zero mode assemble into a new effective field. This new field behaves classically and it is the object which actually rolls down. We show how this reinterpretation saves the standard picture of how metric perturbations are generated during inflation and that the spinodal growth of fluctuations dom- inates the time dependence of the Bardeen variable for superhorizon modes during inflation. We compute the amplitude and index for the spectrum of scalar density and tensor perturbations and argue that in all models of this type the spinodal instabilities are responsible for a ‘red’ spectrum of primor- dial scalar density perturbations. A criterion for the validity of these models is provided and contact with the reconstruction program is established validat- ing some of the results within a non-perturbative framework. The decoherence aspects and the quantum to classical transition through inflation are studied in detail by following the full evolution of the density matrix and relating the classicality of cosmological perturbations to that of long-wavelength matter fluctuations.
College: Faculty of Science and Engineering
Issue: 4
Start Page: 2166
End Page: 2185