Vacuum structure for scalar cosmological perturbations in modified gravity models

Journal Article · Mon Jun 01 00:00:00 EDT 2009 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2009/06/034· OSTI ID:22273163

Felice, Antonio De; Suyama, Teruaki ^[1]

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1. Theoretical and Mathematical Physics Group, Centre for Particle Physics and Phenomenology, Louvain University, 2 Chemin du Cyclotron, 1348 Louvain-la-Neuve (Belgium)

We have found for the general class of Modified Gravity Models f(R, G) a new instability which can arise in vacuum for the scalar modes of the cosmological perturbations if the background is not de Sitter. In particular, the short-wavelength modes, if stable, in general have a group velocity which depends linearly in k, the wave number. Therefore these modes will be in general superluminal. We have also discussed the condition for which in general these scalar modes will be ghost-like. There is a subclass of these models, defined out of properties of the function f(R, G) and to which the f(R) and f(G) models belong, which however do not have this feature.

• OSTI ID: 22273163
• Journal Information: Journal of Cosmology and Astroparticle Physics, Vol. 2009, Issue 06; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1475-7516
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
COSMOLOGICAL MODELS
COSMOLOGY
DE SITTER GROUP
DE SITTER SPACE
DISTURBANCES
GRAVITATION
SCALARS
VELOCITY
WAVELENGTHS