相关论文: Duality in String Cosmology

The aim of this work is to achieve a formulation of the bosonic string theory in which T-duality appears as a manifest symmetry. Two models exhibiting this property are discussed. The first is based on the stringy extension of the…

We describe a novel duality symmetry of Phi(4)-theory defined on noncommutative Euclidean space and with noncommuting momentum coordinates. This duality acts on the fields by Fourier transformation and scaling. It is an extension, to…

In this lecture we address the following issues in the context of string theories: i) The role played by S and T dualities in obtaining topological inflation in N=1 supergravity models, ii) A mechanism to generate the baryon asymmetry of…

We review some formal aspects of cosmological solutions in closed string theory with duality symmetric ``matter'' following recent paper with C. Vafa (HUTP-91/A049). We consider two models : when the matter action is the classical action of…

The duality-type symmetries of string cosmology naturally lead to a pre-big-bang phase of accelerated evolution as dual counterpart of the decelerated expansion of standard cosmology. We discuss several properties of this scenario,…

Representing the data of a string compactified on a circle in the background of H-flux in terms of the geometric data of a principal loop group bundle, we show that T-duality in type II string theory can be understood as the interchange of…

In this article we offer the new interpretation of T-dualization procedure of type II superstring theory in double space framework. We use the ghost free action of type II superstring in pure spinor formulation in approximation of constant…

We consider a codimension-one brane embedded in a gravity-dilaton bulk action, whose symmetries are compatible with T-duality along the space-like directions parallel to the brane, and the bulk time-like direction. The equations of motions…

In string theory, the traditional picture of a Universe that emerges from the inflation of a very small and highly curved space-time patch is a possibility, not a necessity: quite different initial conditions are possible, and not…

Inspired by String T-duality and taking into account the zero-point length correction, $l_0$, to the gravitational potential, we construct modified Friedmann equations by applying the first law of thermodynamics on the apparent horizon of…

T-duality is a symmetry of the heterotic string to all orders in string perturbation theory. This results in an effective four dimensional supergravity theory with desirable features for phenomenology. T-duality, as well as, generically, an…

General ideas of gauge/gravity duality allow for the possibility of time dependent solutions that interpolate between a perturbative gauge theory phase and a weakly curved string/gravity phase. Such a scenario applied to cosmology would…

A geometric string solution has background fields in overlapping coordinate patches related by diffeomorphisms and gauge transformations, while for a non-geometric background this is generalised to allow transition functions involving…

We consider a toy cosmological model in string theory involving the winding and momentum modes of (m,n) strings, i.e. bound states of m fundamental and n D-strings. The model is invariant under S-duality provided that m and n are…

We consider the low-energy effective string action in four dimensions including the leading order-$\alpha'$ terms. An exact homogeneous solution is obtained. It represents a non-singular expanding cosmological model in which the tensor…

We consider the T-duality transformations of the low-energy quantum string theory effective action in the presence of classical fundamental string source and demonstrate explicitly that T-duality still holds.

The S--duality transformations of the lowest order string effective theory admit a space time interpretation for 4-dim backgrounds with one Killing symmetry. Starting from pure gravity and performing a sequence of intertwined T-S-T duality…

This paper investigates the significance of T-duality in string theory: the indistinguishability with respect to all observables, of models attributing radically different radii to space -- larger than the observable universe, or far…

Recent work on the action of T duality on Dirichlet-branes is generalized to the case in which the open string satisfies boundary conditions that are neither Neumann nor Dirichlet. This is achieved by implementing T duality as a canonical…

String cosmology aims at providing a reliable description of the very early Universe in the regime where standard-model physics is no longer appropriate, and where we can safely apply the basic ingredients of superstring models such as…