Related papers: Degenerate and critical domain walls and accelerat…
I give a brief and elementary introduction to braneworld models with large extra dimensions. Three conceptually distinct scenarios are outlined: (i) Large compact extra dimensions; (ii) Warped extra dimensions; (iii) Infinite-volume extra…
Discrete symmetries are commonplace in field theoretical models but pose a severe problem for cosmology since they lead to the formation of domain walls during spontaneous symmetry breaking in the early universe. However if one of the…
We consider static, axisymmetric, thick brane solutions on higher dimensional, spherically symmetric black hole backgrounds. It was found recently [1], that in cases when the thick brane has more than 2 spacelike dimensions, perturbative…
We consider a Friedmann model of the universe with bulk viscous matter and radiation as the cosmic components. We study the asymptotic properties in the equivalent phase space by considering the three cases for the bulk viscous coefficient…
Cosmology is usually understood as an observational science, where experimentation plays no role. It is interesting, nevertheless, to change this perspective addressing the following question: what should we do to create a universe, in a…
We assume that the universe consists of clusters which in turns have sub-clusters and the sub-clusters have sub-subclusters and so on. Confining to three-dimensional space, it is shown that the universe is expanding if entropy of the…
Domain walls, arising from the spontaneous breaking of a discrete symmetry, can be coupled to charge carriers. In much the same way as the Witten model for superconducting cosmic string, an investigation is made here in the case of…
The theory for the selection of the initial state of the universe from the landscape multiverse predicts superhorizon inhomogeneities induced by nonlocal entanglement of our Hubble volume with modes and domains beyond the horizon. Here we…
It is proposed four dimensional curved space-time with de-Sitter group of motion. Theory contain free dimension constants of length, impulse and action. Under infinite values of these parameters theory pass to usual Minkowski space-time…
In this article, we study the effect of the universe accelerating expansion on the structure of the general relativistic thick disks. Hence, by applying a conformal transformation on the metric of a static disk in isotropic coordinates, we…
One of the most important discoveries in modern cosmology is cosmic acceleration. However, we find that today's universe could decelerate in the statistically preferred Chevallier-Polarski-Linder (CPL) scenario over the $\Lambda$CDM model…
We introduce an effective Lagrangian which describes the classical and semiclassical dynamics of spherically symmetric, self-gravitating objects that may populate the Universe at large and small (Planck) scale. These include wormholes,…
Recent observations on the large-scale structure of the universe indicate that the cosmological constant cannot be the definitive answer to the nature of dark energy. Therefore, it is a good time to propose alternatives to understand the…
We propose new braneworld models arising from a scalar field in the bulk. In these examples, the induced on--brane line element is de Sitter (or anti de Sitter) and the bulk (five dimensional) Einstein equations can be exactly solved to…
There has been recent interest in new types of topological defects arising in models with compact extra dimensions. We discuss in this context the old statement that if only SU(N) gauge fields and adjoint matter live in the bulk, and the…
We present a model with an infinite volume bulk in which a braneworld with a cosmological constant evolves to a static, 4-dimensional Minkowski spacetime. This evolution occurs for a generic class of initial conditions with positive energy…
Whether our universe with present day acceleration can eventually collapse is very interesting problem. We are also interesting in such problems, whether the universe is closed? Why it is so flat? How long to expend a period for a cycle of…
In a recent paper [arXiv:1206.4916] by T. Padmanabhan, it was argued that our universe provides an ideal setup to stress the issue that cosmic space is emergent as cosmic time progresses and that the expansion of the universe is due to the…
We study a 5-dimensional $f({\cal R})$ brane gravity within the framework of scalar-tensor type theories. We show that such a model predicts, for a certain choice of $f({\cal R})$ and a spatially flat universe, an exponential potential,…
We construct a family of (p+3)-dimensional brane worlds in which the brane has one compact extra dimension, the bulk has two extra dimensions, and the bulk closes regularly at codimension two submanifolds known as bolts. The…