Related papers: Tachyon cosmology with non-vanishing minimum poten…
We study the dynamics of a D3-brane moving in the background of a bulk tachyon field of a D3-brane solution of Type-0 string theory. We show that the dynamics on the probe D3-brane can be described by a geometrical tachyon field rolling…
The study of open string tachyon condensation in string field theory can be drastically simplified by making an appropriate choice of coordinates on the space of string fields. We show that a very natural coordinate system is suggested by…
Using tachyon or quintessence fields along with a barotropic fluid on the brane we examine the different cosmological stages in a Friedmann-Robertson-Walker(FRW) universe, from the first radiation scenario to the later era dominated by…
We present a comprehensive study of the cosmological solutions of 6D braneworld models with azimuthal symmetry in the extra dimensions, moduli stabilization by flux or a bulk scalar field, and which contain at least one 3-brane that could…
We consider an unstable bound system of two supersymmetric Dirichlet branes of different dimensionality ($p,p'$ with $p'<p$) embedded in a flat non-compactified IIA or IIB type background. We study the decay, via tachyonic condensation, of…
In this note we propose the use of an alternate action for the open string tachyon on a non-BPS $D3$-brane. At the classical level this action is precisely equivalent to the more commonly used DBI action, but involves an additional coupling…
We analyze the fate of excitations in regions of closed string tachyon condensate, a question crucial for understanding unitarity in a class of black holes in string theory. First we introduce a simple new example of {\it quasilocal}…
The emergence of the cosmological composition (the reheating era) after the inflationary period is analyzed in the framework of the braneworld models, in which our Universe is a three-brane embedded in a five-dimensional bulk, by assuming…
We consider several classes of noncommutative inflationary models within an extended version of patch cosmological braneworlds, starting from a maximally invariant generalization of the action for scalar and tensor perturbations to a…
The method of probe brane is the powerful one to obtain the effective action living on the probe brane from supergravity. We apply this method to the unstable brane systems, and understand the tachyon condensation in the context of the…
We derive the analogue of the vanishing of the cosmological constant in 3+1 dimensions, T_0^0 = 0, in terms of an integral over components of the energy-momentum tensor of a 4+1 dimensional universe with parallel three-branes, and an…
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…
Five-dimensional cosmological models with two 3-branes and with a buck cosmological constant are studied. It is found that for all the three cases ($\Lambda =0$, $\Lambda >0$, and $\Lambda <0$), the conventional space-time singularity ``big…
We study cosmological solutions in the context of 4-dimensional low energy Heterotic M-theory with moving bulk branes. In particular we present non-trivial, analytic axion solutions generated by new symmetries of the full potential-free…
In the present work we study a dark energy model in which a non-linear scalar field (tachyon) with a Born-Infeld type of action is responsible for the observed cosmic acceleration. The potential of the tachyon is well-motivated since it…
Here, non-minimally coupled tachyon to gravity is considered as a source of "dark energy". It is demonstrated that with expansion of the universe, tachyon dark energy decays to "dark matter" providing a solution to "cosmic coincidence…
We apply a very simple procedure to construct non-singular cosmological models for flat Friedmann universes filled with minimally coupled scalar fields or by tachyon Born-Infeld-type fields. Remarkably, for the minimally coupled scalar…
We present a non-compact (4 + 1) dimensional model with a local strong four-fermion interaction supplementing it with gravity. In the strong coupling regime it reveals the spontaneous translational symmetry breaking which eventually leads…
In this paper we will study the quantum field theory of fluctuation modes around the classical solution that describes tachyon condensation on unstable D-brane.We will calculate the number of particle produced near the beginning of the…
Phantom cosmology allows to account for dynamics and matter content of the universe tracing back the evolution to the inflationary epoch, considering the transition to the non-phantom standard cosmology (radiation/matter dominated eras) and…