Related papers: Cosmological constant is probably adjustable in br…
To solve the cosmological constant fine tuning problem, we investigate a $(n+1)$-dimensional generalized Randall-Sundrum brane world scenario with two $(n-1)$-branes instead of two 3-branes. Adopting an anisotropic metric ansatz, we obtain…
We modify and extend an earlier proposal by Brown and Teitelboim to relax the effective cosmological term by nucleation of branes coupled to a three-index gauge potential. Microscopic considerations from string/M theory suggest two major…
The cosmological constant problem and brane universes are reviewed briefly. We discuss how the cosmological constant problem manifests itself in various scenarios for brane universes. We review attempts - and their difficulties - that aim…
We investigate a simple braneworld model in which the universe contains only cold dark matter and a cosmological constant, but the effective dark energy is phantom-like because of extra-dimensional gravity effects. Modified gravity screens…
As shown by Parker and Raval, quantum field theory in curved spacetime gives a possible mechanism for explaining the observed recent acceleration of the universe. This mechanism, which differs in its dynamics from quintessence models,…
We show that a self-tuning mechanism of the cosmological constant could work in 5D non-compact space-time with a $Z_2$ symmetry in the presence of a massless scalar field. The standard model matter fields live only on the 4D brane. The…
We have studied the curvaton scenario in brane world cosmology in an intermediate inflationary scenario. This approach has allowed us to find some constraints on different parameters that appear in the model.
We argue that traditional methods of compactification of string theory make it very difficult to understand how the cosmological constant becomes zero. String inspired models can give zero cosmological constant after fine tuning but since…
We investigate observational constraints on the curvature of the universe not restricting ourselves to a cosmological constant as dark energy, in particular allowing a dark energy equation of state to evolve with time in several ways. We…
We examine, in the context of certain string compactifications resulting in five dimensional brane worlds the mechanisms of (self) tuning of the cosmological constant and the recovery of standard cosmological evolution. We show that self…
We construct a cosmological model based on a free particle model which is constrained on an embedded toroidal brane, with a general rotation around a specific axis in the bulk space. Some related issues such as the rotation axis of the…
We introduce "anamorphic" cosmology, an approach for explaining the smoothness and flatness of the universe on large scales and the generation of a nearly scale-invariant spectrum of adiabatic density perturbations. The defining feature is…
The cosmology of the Randall-Sundrum scenario for a positive tension brane in a 5-D Universe with localized gravity has been studied extensively recently. Here we extend it to more general situations. We consider the time-dependent…
Big Bang models of the Universe predict rapid domination by curvature, a paradox known as the flatness problem. Solutions to this problem usually leave the Universe exactly flat for every practical purpose. Explaining a nearly but not…
We consider brane cosmologies within the context of five-dimensional actions with O(a') higher curvature corrections. The actions are compatible with bulk string amplitude calculations from heterotic string theory. We find wrapped solutions…
In braneworld models a variable vacuum energy may appear if the size of the extra dimension changes during the evolution of the universe. In this scenario the acceleration of the universe is related not only to the variation of the…
This work investigates the cosmology of a thick brane within the context of $f(\mathbb{Q})$ gravity, an extension of symmetric teleparallelism. Using a five-dimensional Friedmann-Lema\^itre-Robertson-Walker metric, we solve the field…
Light scalar fields very naturally appear in modern cosmological models, affecting such parameters of Standard Model as electromagnetic fine structure constant $\alpha$, dimensionless ratios of electron or quark mass to the QCD scale,…
We study a varying electric charge brane world cosmology in the RS2 model obtained from a varying-speed-of-light brane world cosmology by redefining the system of units. We elaborate conditions under which the flatness problem and the…
We consider an infinite-volume brane world setup where a codimension one brane is coupled to bulk gravity plus a scalar field with vanishing potential. The latter is protected by bulk supersymmetry, which is intact even if brane…