A Back-reaction Induced Lower Bound on the Tensor-to-Scalar Ratio

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dc.creatorMartineau, P.
dc.creatorBrandenberger, R.
dc.date2007-09-17
dc.date2007-10-10
dc.date.accessioned2026-07-07T11:37:14Z
dc.date.available2026-07-07T11:37:14Z
dc.descriptionThere are large classes of inflationary models, particularly popular in the context of string theory and brane world approaches to inflation, in which the ratio of linearized tensor to scalar metric fluctuations is very small. In such models, however, gravitational waves produced by scalar modes cannot be neglected. We derive the lower bound on the tensor-to-scalar ratio by considering the back-reaction of the scalar perturbations as a source of gravitational waves. These results show that no cosmological model that is compatible with a metric scalar amplitude of $\approx 10^{-5}$ can have a ratio of the tensor to scalar power spectra less than $\approx 10^{-8}$ at recombination and that higher-order terms leads to logarithmic growth for r during radiation domination. Our lower bound also applies to non-inflationary models which produce an almost scale-invariant spectrum of coherent super-Hubble scale metric fluctuations.
dc.description5 pages, version 3, minor changes from version 2
dc.identifierhttps://arxiv.org/abs/0709.2671
dc.identifierhttp://arxiv.org/abs/0709.2671
dc.identifierMod.Phys.Lett.A23:727-735,2008
dc.identifierdoi:10.1142/S0217732308026777
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/199139
dc.subjectAstrophysics
dc.subjectGeneral Relativity and Quantum Cosmology
dc.subjectHigh Energy Physics - Phenomenology
dc.subjectHigh Energy Physics - Theory
dc.titleA Back-reaction Induced Lower Bound on the Tensor-to-Scalar Ratio
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