Dynamics of the universe as a "test 3-brane" in a 5D bulk

In this paper we study the dynamics of a 5D bulk space-time with our universe as a "test 3-brane" located in the bulk, an idealized model of a topological object whose physical properties is negligible in comparison with that of the bulk. Our universe experiences acceleration and its equation of state parameter crosses the phantom divide line due to the geometry of the bulk space-time.Comment: 11 pages, 12 figures; will be published in Can. J. Phy

Curvaton reheating and intermediate inflation in brane cosmology

In this paper, we study the curvaton reheating mechanism for an intermediate inflationary universe in brane world cosmology. In contrast to our previous work, we assume that when the universe enters the kination era, it is still in the high-energy regime. We then discuss, in detail, the new cosmological constraints on both the model parameters and the physical quantities.Comment: 15 pages, 4 figures. With some modifications to the text the version published on Can. J. Phys. arXiv admin note: significant text overlap with arXiv:1011.080

Constraints on scalar-tensor theories from observations

We study the dynamical description of scalar-tensor gravity by performing the best-fit analysis for two cases of exponential and power-law form of the potential and scalar field function coupled to the curvature. The models are then tested against observational data. The results show that in both scenarios the Universe undergoes an acceleration expansion period and the geometrical equivalent of dark energy is associated with a time-dependent equation of state.Comment: 16 pages, 32 figure