Realizing Scale-invariant Density Perturbations in Low-energy Effective String Theory

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dc.creatorGuo, Zong-Kuan
dc.creatorOhta, Nobuyoshi
dc.creatorTsujikawa, Shinji
dc.date2006-11-01
dc.date2007-01-09
dc.date.accessioned2026-07-07T11:22:55Z
dc.date.available2026-07-07T11:22:55Z
dc.descriptionWe discuss the realization of inflation and resulting cosmological perturbations in the low-energy effective string theory. In order to obtain nearly scale-invariant spectra of density perturbations and a suppressed tensor-to-scalar ratio, it is generally necessary that the dilaton field $ϕ$ is effectively decoupled from gravity together with the existence of a slowly varying dilaton potential. We also study the effect of second-order corrections to the tree-level action which are the sum of a Gauss-Bonnet term coupled to $ϕ$ and a kinetic term $(\nabla ϕ)^4$. We find that it is possible to realize observationally supported spectra of scalar and tensor perturbations provided that the correction is dominated by the $(\nabla ϕ)^4$ term even in the absence of the dilaton potential. When the Gauss-Bonnet term is dominant, tensor perturbations exhibit violent negative instabilities on small-scales about a de Sitter background in spite of the fact that scale-invariant scalar perturbations can be achieved.
dc.description13 pages; v2: minor corrections, refs. added, version to appear in PRD
dc.identifierhttps://arxiv.org/abs/hep-th/0610336
dc.identifierhttp://arxiv.org/abs/hep-th/0610336
dc.identifierPhys.Rev.D75:023520,2007
dc.identifierdoi:10.1103/PhysRevD.75.023520
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/194737
dc.subjectHigh Energy Physics - Theory
dc.subjectAstrophysics
dc.subjectGeneral Relativity and Quantum Cosmology
dc.subjectHigh Energy Physics - Phenomenology
dc.titleRealizing Scale-invariant Density Perturbations in Low-energy Effective String Theory
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