Related papers: D-branes, String Cosmology and Large Extra Dimensi…
Within the framework of a five-dimensional brane world with a stabilized radion, we compute the cosmological perturbations generated during inflation and show that the perturbations are a powerful tool to probe the physics of extra…
In a previous publication by some of the authors (N.E.M., M.S. and M.F.Y.), we have argued that the "D-material universe", that is a model of a brane world propagating in a higher-dimensional bulk populated by collections of D-particle…
We consider a six dimensional brane world model, where the brane is described by a localized solution to the baby-Skyrme model extending in the extradimensions. The branes have a cosmological constant modeled by inflating four dimensional…
Unstable, non-BPS D-branes in weakly coupled ten dimensional string theory have many mysterious properties. Among other things, it is not clear what sets their tension, what is their relation to the better understood BPS D-branes, and why…
We consider the anisotropic evolution of spatial dimensions and the stabilization of internal dimensions in the framework of brane gas cosmology. We observe that the bulk RR field can give an effective potential which prevents the internal…
In brane inflationary scenarios, the cosmological perturbations are supposed to originate from the vacuum fluctuations of the inflaton field corresponding to the position of the brane. We show that a significant, and possibly dominant,…
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…
We study the dilaton stabilization in the D-brane world in which a D-brane constitutes our universe. The dilaton can be stabilized due to the interplay between the D-brane tension and the negative scalar curvature of extra dimensions.…
We argue that the cosmological constant problem can be solved in a braneworld model with infinite-volume extra dimensions, avoiding no-go arguments applicable to theories that are four-dimensional in the infrared. Gravity on the brane…
We present several higher-dimensional spacetimes for which observers living on 3-branes experience an induced metric which bounces. The classes of examples include boundary branes on generalised S-brane backgrounds and probe branes in…
We discuss a new mechanism of obtaining a period of cosmological inflation in the context of string theory. This mechanism is based on embedded defects which form dynamically on higher dimensional D-branes. Such defects generate topological…
In certain implementations of the brane inflationary paradigm, the exit from inflation occurs when the branes annihilate through tachyon condensation. We investigate various cosmological effects produced by this tachyonic era. We find that…
Large extra dimensions provide interesting extensions of our parameter space for gravitational theories. There exist now brane models which can perfectly reproduce standard four-dimensional Friedmann cosmology. These models are not…
We study the regularization of theories of ``brane induced'' gravity in codimension $N>1$. The brane can be interpreted as a thin dielectric with a large dielectric constant, embedded in a higher dimensional space. The kinetic term for the…
We study the cosmological evolution of extended branes in 6D warped flux compactification models. The branes are endowed with the three ordinary spatial dimensions, which are assumed to be homogeneous and isotropic, as well as an internal…
We provide a pedagogical overview of inflation in string theory. Our theme is the sensitivity of inflation to Planck-scale physics, which we argue provides both the primary motivation and the central theoretical challenge for the subject.…
A brane universe moving in a curved higher dimensional bulk space is considered. The motion induces a cosmological evolution on the universe brane that is indistiguishable from a similar one induced by matter density on the brane. The…
We study a moving D-brane in a time-dependent background. There is particle production both because of non-trivial cosmological evolution, and by closed string emission from the brane that gradually decelerates due to a gain in mass. The…
We discuss how Starobinsky-like inflation may emerge from dilaton dynamics in brane cosmology scenarios based on string theory, in which our universe is represented as a three-brane. The effective potential may acquire a constant term from…
Models with extra dimensions have attracted much interest recently because they may provide the solution for long standing problems in physics. One interesting and very attractive idea is that our visible universe is confined to a…