Cosmological perturbations from braneworld inflation with a Gauss-Bonnet term

Journal Article · Fri Oct 15 04:00:00 EDT 2004 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PhysRevD.70.083525· OSTI ID:20705459

Dufaux, Jean-Francois ^[1]; Lidsey, James E ^[2]; Maartens, Roy ^[3]; Sami, M ^[4]

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1. LPT, Universite de Paris-Sud, 91405 Orsay (France)
2. Astronomy Unit, School of Mathematical Sciences, Queen Mary, University of London, London E1 4NS (United Kingdom)
3. Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 2EG (United Kingdom)
4. Inter-University Centre for Astronomy and Astrophysics, Pune (India)

Braneworld inflation is a phenomenology related to string theory that describes high-energy modifications to general relativistic inflation. The observable universe is a brane embedded in 5-dimensional anti de Sitter spacetime. When the 5-dimensional action is Einstein-Hilbert, we have a Randall-Sundrum type braneworld. The amplitude of tensor and scalar perturbations from inflation is strongly increased relative to the standard results, although the ratio of tensor to scalar amplitudes still obeys the standard consistency relation. If a Gauss-Bonnet term is included in the action, as a high-energy correction motivated by string theory, we show that there are important changes to the Randall-Sundrum case. We give an exact analysis of the tensor perturbations. They satisfy the same wave equation and have the same spectrum as in the Randall-Sundrum case, but the Gauss-Bonnet change to the junction conditions leads to a modified amplitude of gravitational waves. The amplitude is no longer monotonically increasing with energy scale, but decreases asymptotically after an initial rise above the standard level. Using an approximation that neglects bulk effects, we show that the amplitude of scalar perturbations has a qualitatively similar behavior to the tensor amplitude. In addition, the tensor to scalar ratio breaks the standard consistency relation.

• OSTI ID: 20705459
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 8 Vol. 70; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
AMPLITUDES
CORRECTIONS
COSMOLOGY
DE SITTER GROUP
DISTURBANCES
EINSTEIN FIELD EQUATIONS
GRAVITATION
GRAVITATIONAL WAVES
MEMBRANES
QUANTUM FIELD THEORY
RELATIVISTIC RANGE
SCALARS
SPACE-TIME
STRING MODELS
TENSORS
UNIVERSE
WAVE EQUATIONS