253 research outputs found
De Sitter stability in quadratic gravity
Quadratic curvature corrections to Einstein-Hilbert action lead in general to
higher-order equations of motion, which can induced instability of some
unperturbed solutions of General Relativity. We study conditions for stability
of de Sitter cosmological solution. We argue that simple form of this condition
known for FRW background in 3+1 dimensions changes seriously if at least one of
these two assumptions is violated. In the present paper the stability
conditions for de Sitter solution have been found for multidimensional FRW
background and for Bianchi I metrics in 3+1 dimensions.Comment: 12 pages with 4 figures; references adde
Regular and Chaotic Regimes in Scalar Field Cosmology
A transient chaos in a closed FRW cosmological model with a scalar field is
studied. We describe two different chaotic regimes and show that the type of
chaos in this model depends on the scalar field potential. We have found also
that for sufficiently steep potentials or for potentials with large
cosmological constant the chaotic behavior disappears.Comment: Published in SIGMA (Symmetry, Integrability and Geometry: Methods and
Applications) at http://www.emis.de/journals/SIGMA
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