Related papers: Modified Friedmann Equation and Inflation in Warpe…
As a first step towards inflation in genuinely F-theoretic setups, we propose a scenario where the inflaton is the relative position of two 7-branes on holomorphic 4-cycles. Non-supersymmetric gauge flux induces an attractive inter-brane…
It has very recently been realized that coupling branes to higher dimensional quantum gravity theories and considering the consistency of what lives on the branes, one is able to understand whether such theories can belong either to the…
Upper bounds on the energy scale at the end of inflation in the Randall-Sundrum type II braneworld scenario are derived. The analysis is made exact by introducing new parameters that represent extensions of the Hubble flow parameters. Only…
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…
We consider an inflationary scenario in the holographic braneworld with a cosmological fluid occupying the 3+1 dimensional brane located at the holographic boundary of an asymptotic ADS$_5$ bulk. The contribution of the boundary conformal…
The modified gravitational equations to describe a four-dimensional braneworld in the case with the Lorentz invariant violation in a bulk spacetime is presented. It contains a trace part of the brane energy-momentum tensor and the…
In string theory, even when there are ten to the thousand power vacuum states, does inflation produce overwhelmingly one preferred type of vacuum state? We respond affirmatively to questions whether existence of graviton production is…
A five-dimensional solution to Einstein's equations coupled to a scalar field has been proposed as a partial solution to the cosmological constant problem: the effect of arbitrary vacuum energy (tension) of a 3-brane is cancelled; however,…
We consider inflaton potential reconstruction in the context of the simplest braneworld scenario, where both the Friedmann equation and the form of scalar and tensor perturbations are modified at high energies. We derive the reconstruction…
We study an effective four-dimensional theory with an action with two scalar fields minimally coupled to gravity, and with a matter action which couples to the two scalar fields via an overall field-dependent coefficient in the action. Such…
The radion in the Randall-Sundrum model is stabilized by the back reaction of a bulk scalar field with its VEV depending on the fifth dimensional coordinate. We studied the radion dynamics in an extended scenario, where intermediate branes…
We consider the Einstein equations within the DBI scenario for a spatially flat Friedmann-Robertson-Walker (FRW) spacetime without a cosmological constant. We derive the inflationary scenario by applying the symmetry transformations which…
We explore the mechanics of inflation in simplified extra-dimensional models involving an inflaton interacting with the Einstein-Maxwell system in two extra dimensions. The models are Goldilocks-like in that they are just complicated enough…
We study two $(4+n)$-dimensional branes embedded in $(5+n)$-dimensional spacetime. Using the gradient expansion approximation, we find that the effective theory is described by $(4+n)$-dimensional scalar-tensor gravity with a specific…
We demonstrate an inflationary solution to the cosmological horizon problem during the Hagedorn regime in the early universe. Here the observable universe is confined to three spatial dimensions (a three-brane) embedded in higher…
We demonstrate an inflationary solution to the cosmological horizon problem during the Hagedorn regime in the early universe. Here the observable universe is confined to three spatial dimensions (a three-brane) embedded in higher…
In hybrid inflation models, typically only a tiny fraction of possible initial conditions give rise to successful inflation, even if one assumes spatial homogeneity. We analyze some possible solutions to this initial conditions problem,…
We discuss a five dimensional inflationary scenario based on a supersymmetric SO(10) model compactified on $S^1/(Z_2\times Z_2')$. Inflation is implemented through scalar potentials on four dimensional branes, and a brane-localized…
We confront the recent proposal of Emerging Brane Inflation with WMAP3+SDSS, finding a scalar spectral index of $n_s=0.9659^{+0.0049}_{-0.0052}$ in excellent agreement with observations. The proposal incorporates a preceding phase of…
We examine the full nonlinear dynamics of closed FRW universes in the framework of D-branes formalism. Friedmann equations contain additional terms arising from the bulk-brane interaction that provide a concrete model for nonsingular…