2004/06/30 by Shinji Tsujikawa, M. Sami, Roy Maartens
Mathematics · Physics and Astronomy · #Black Holes and Theoretical Physics #Brane #Cosmology and Gravitation Theories #Einstein #Galaxies: Formation, Evolution, Phenomena #Gauss–Bonnet theorem #General relativity #Geometry #Mathematical physics #Mathematics #Physics #Quadratic equation #Quartic function #Randall–Sundrum model #Theoretical physics #astro-ph #gr-qc #hep-ph #hep-th
paper · pdf · doi:10.1103/physrevd.70.063525
published as Phys.Rev. D70 (2004) 063525 · 10 pages, 10 figures, version to appear in Physical Review D
arxiv created 2004/08/26 · openalex publication_date 2004/09/22 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
High-energy modifications to general relativity introduce changes to the perturbations generated during inflation, and the latest high-precision cosmological data can be used to place constraints on such modified inflation models. Recently it was shown that Randall-Sundrum--type braneworld inflation leads to tighter constraints on quadratic and quartic potentials than in general relativity. We investigate how this changes with a Gauss-Bonnet correction term, which can be motivated by string theory. Randall-Sundrum models preserve the standard consistency relation between the tensor spectral index and the tensor-to-scalar ratio. The Gauss-Bonnet term breaks this relation, and also modifies the dynamics and perturbation amplitudes at high energies. We find that the Gauss-Bonnet term tends to soften the Randall-Sundrum constraints. The observational compatibility of the quadratic potential is strongly improved. For a broad range of energy scales, the quartic potential is rescued from marginal rejection. Steep inflation driven by an exponential potential is excluded in the Randall-Sundrum case, but the Gauss-Bonnet term leads to marginal compatibility for sufficient e-folds.