Related papers: Tilted String Cosmologies
We construct new classes of cosmological solution to the five dimensional Einstein-Maxwell-dilaton theory, that are non-stationary and almost conformally regular everywhere. The base geometry for the solutions is the four-dimensional…
Arguably the simplest model of a cosmological singularity in string theory, the Lorentzian orbifold $\Real^{1,1}/boost$ is known to lead to severe divergences in scattering amplitudes of untwisted states, indicating a large backreaction…
It is shown that any anisotropic and inhomogeneous cosmological solution to the lowest-order, four-dimensional, dilaton-graviton string equations of motion may be employed as a seed to derive a curved, three-brane cosmological solution to…
Self-consistent solutions to nonlinear spinor field equations in General Relativity have been studied for the case of Bianchi type-I space-time filled with perfect fluid. The initial and the asymptotic behavior of the field functions and…
In this paper, we have investigated some features of anisotropic accelerating Bianchi type-I cosmological model in the presence of two non-interacting fluids, i.e. one usual string and other dark energy fluid towards the gravitational field…
Over the past three decades, considerable effort has been devoted to studying the rich and diverse phenomenologies of heterotic strings exhibiting spacetime supersymmetry. Unfortunately, during this same period, there has been relatively…
String gas cosmology is rewritten in the Einstein frame. In an effective theory in which a gas of closed strings is coupled to a dilaton gravity background without any potential for the dilaton, the Hagedorn phase which is quasi-static in…
We present a new class of exact homogeneous cosmological solutions with a radiation fluid for all scalar-tensor theories. The solutions belong to Bianchi type $VI_{h}$ cosmologies. Explicit examples of nonsingular homogeneous scalar-tensor…
We determine a consistent phase space for a theory consisting in the Einstein-Hilbert action coupled to matter fields (dilaton, one-form, two-form) and containing three-dimensional black strings (the Horne-Horowitz solution and…
Smooth Cauchy data for the Einstein-Lambda-vacuum field equations with positive cosmological constant Lambda that are sufficiently close to de Sitter data develop into a solution that admits a smooth conformal boundary Scri+ in its future.…
In this paper we show that the spatially homogeneous Bianchi type I and Kantowski-Sachs cosmologies derived from the Brans-Dicke theory of gravity admit a supersymmetric extension at the quantum level. Global symmetries in the effective…
We present an explicit three-parameter class of $p=\gamma \varrho$, ($-1/3\leq\gamma<1$), cosmological models admitting a two-dimensional group $G_{2}$ of isometries acting on spacelike surfaces. The family is self-similar in the sense that…
A self-consistent system of interacting spinor and scalar fields is considered within the scope of Bianchi type VI cosmological model filled with a perfect fluid. The contribution of the cosmological constant ($\Lambda$-term) is taken into…
The present study deals with locally rotationally symmetric (LRS) Bianchi type II cosmological models representing massive string. The energy-momentum tensor for such string as formulated by Letelier (1983) is used to construct massive…
Considering the linearized gravity with matter fields, the effective potential of the ``conformal dilaton'' in the string frame is generated semiclassically by one-loop contribution of heavy matter fields. This in turn generates a…
We derive the late-time behaviour of tilted Bianchi VII_0 cosmologies with an irrotational radiation fluid as source, and give the asymptotic form of the general solution as $t \to +\infty$, making comparisons with the dust-filled models.…
A new class of a spatially homogeneous and anisotropic Bianchi type-I cosmological models of the universe for perfect fluid distribution within the framework of scalar-tensor theory of gravitation proposed by Saez and Ballester (Phys. Lett.…
Demanding $O(d,d)$-duality covariance, Hohm and Zwiebach have written down the action for the most general cosmology involving the metric, $b$-field and dilaton, to all orders in $\alpha'$ in the string frame. Remarkably, for an FRW…
Using the renormalization-group formalism, a sigma model of a special type- in which the metric and the dilaton depend explicitly on one of the string coordinates only-is investigated near two dimensions. It is seen that dilatonic gravity…
Aspects of superstring cosmology are reviewed with an emphasis on the cosmological implications of duality symmetries in the theory. The string effective actions are summarized and toroidal compactification to four dimensions reviewed.…