Related papers: Dilaton Production in String Cosmology

We present a wholly self-consistent, complete cyclic bouncing cosmology based on components drawn from string theory and constructed in a way that is under perturbative control throughout (e.g., with temperature much less than the string…

We present a new approach to early universe cosmology. Inflation is replaced by a phase transition in which both matter and geometry are created simultaneously. We calculate the spectrum of metric perturbations and show that it is flat. We…

Pre--big bang models of inflation based on string cosmology produce a stochastic gravitational wave background whose spectrum grows with decreasing wavelength, and which may be detectable using interferometers such as LIGO. We point out…

In this thesis, consisting of two main parts, we study observational signatures of cosmic (super)strings in the context of D-brane inflation and properties of scalar perturbations on generic homogeneous inflating backgrounds. In the first…

We consider early time cosmic evolution in string gas cosmology dominated by open strings attached to D-branes. After reviewing statistical properties of open strings in D-brane backgrounds, we use dilaton-gravity equations to determine the…

We analyze homogeneous anisotropic cosmology driven by the dilaton and the self-interacting ``massive'' antisymmetric tensor field which are indispensable bosonic degrees with the graviton in the NS-NS sector of string theories with…

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…

We present analytic formulae for the integral number count distribution of cosmological bursting or steady sources valid over the entire range of fluxes, including density evolution and either standard candle or a power law luminosity…

We study the cosmological evolution of a D3-brane Universe in a type 0 string background. We follow the brane universe along the radial coordinate of the background and we calculate the energy density which is induced on the brane because…

We elaborated the gravitational collapse of a self-gravitating complex charged scalar field in the context of the low-energy limit of the string theory, the so-called dilaton gravity. We begin with the regular spacetime and follow the…

We obtain cosmological constraints on models of inflation which exhibit rapid roll solutions. Rapid roll attractors exist for potentials with large mass terms and are thus of interest for inflationary model building within string theory. We…

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,…

We study cosmological backgrounds from the point of view of the dS/CFT correspondence and its renormalization group flow extension. We focus on the case where gravity is coupled to a single scalar with a potential. Depending on the latter,…

Using the dS/QFT correspondence in the context of inflation allows for the study of interesting, otherwise inaccessible physics. In particular, by studying inflation via its dual field theory at the boundary of the de Sitter space, it may…

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 show that, in the presence of a string gas, simple higher-derivative modifications to the effective action for gravity can lead to bouncing and cyclic cosmological models. The modifications bound the expansion rate and avoid…

In this paper, we investigate D-term inflation within the framework of supergravity, employing the minimal K\"{a}hler potential. Following previous studies that revealed that this model can overcome the $\eta$-problem found in F-term…

We examine the field equations of a self-gravitating texture in low-energy superstring gravity, allowing for an arbitrary coupling of the texture field to the dilaton. Both massive and massless dilatons are considered. For the massless…

The interplay of dilatonic effects in dilaton cosmology and stochastic quantum space-time defects within the framework of string/brane cosmologies is examined. The Boltzmann equation describes the physics of thermal dark-matter-relic…

We examine the spectrum of gravitational radiation emitted by a network of cosmic strings, with emphasis on the observational constraints and the opportunities for detection. The analysis improves over past work, as we use a…