2006/10/31 by Tsutomu Kobayashi, Masato Minamitsuji
Physics and Astronomy · #Black Holes and Theoretical Physics #Cosmology and Gravitation Theories #Noncommutative and Quantum Gravity Theories #astro-ph #gr-qc #hep-th
paper · pdf · doi:10.1088/1475-7516/2006/12/008
published as JCAP0612:008,2006 · 18 pages, v2: minor changes, reference added, v3: comments and references added, accepted for publication in JCAP
arxiv created 2006/11/22 · openalex publication_date 2006/12/07 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/30
We study scalar cosmological perturbations in a braneworld model with a bulk Gauss–Bonnet term. For an anti-de Sitter bulk, the five-dimensional perturbation equations share the same form as in the Randall–Sundrum model, which allows us to obtain metric perturbations in terms of a master variable. We derive the boundary conditions for the master variable from the generalized junction conditions on the brane. We then investigate several limiting cases in which the junction equations are reduced to a feasible level. In the low energy limit, we confirm that the standard result of four-dimensional Einstein gravity is reproduced on large scales, whereas on small scales we find that the perturbation dynamics is described by the four-dimensional Brans–Dicke theory. In the high energy limit, all the non-local contributions drop off from the junction equations, leaving a closed system of equations on the brane. We show that, for inflation models driven by a scalar field on the brane, the Sasaki–Mukhanov equation holds on the high energy brane in its original four-dimensional form.