Related papers: Particle production in string cosmology models
We discuss the generation and evolution of density perturbations during the large curvature phase of string cosmology. We find that perturbations in the scalar components of the metric evolve with cosmic time as $\exp (\gamma H_st)$ where…
We investigate the nucleation of circular cosmic strings in models of generalized inflationary universes with an accelerating scale factor. We consider toy cosmological models of a smooth inflationary exit and transition into a flat…
String theory abounds with light scalar fields (the dilaton and various moduli) which create a host of observational problems, and notably some serious cosmological difficulties similar to the ones associated with the Polonyi field in the…
The particle production process is reviewed, through which cosmic inflation can produce a scale invariant superhorizon spectrum of perturbations of suitable fields starting from their quantum fluctuations. Afterwards, in the context of the…
We propose to uncover the signature of a stringy era in the primordial Universe by searching for a prominent peak in the relic graviton spectrum. This feature, which in our specific model terminates an $\omega^3$ increase and initiates an…
We study cosmological solutions to the low-energy effective action of heterotic string theory including possible leading order $\alpha'$ corrections and a potential for the dilaton. We consider the possibility that including such stringy…
We develop a string-inspired model for particle cosmology, based on a flipped SU(5)$\times$U(1) gauge group formulated in a no-scale supergravity framework. The model realizes Starobinsky-like inflation, which we assume to be followed by…
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…
We give a simple derivation of a new formal expression for the number of particles produced from a conformal scalar field vacuum due to the creation of a gauge cosmic string. We find that the number of particles released in string formation…
We describe the detailed study and results of high-resolution numerical simulations of string-induced structure formation in open universes and those with a non-zero cosmological constant. The effect from small loops generated from the…
Cosmic string networks generate cosmological perturbations actively throughout the history of the universe. Thus, the string sourced anisotropy of the cosmic microwave background is not affected by Silk damping as much as the anisotropy…
Cosmic strings are topological defects possibly formed in the early Universe, which may be observable due to their gravitational effects on the cosmic microwave background radiation or gravitational wave experiments. To this effect it is…
Using the kinetic approach, we study the impact of the charged particles dynamics due to the Schwinger effect on the electric field evolution during inflation. As a simple model of the electric field generation, we consider the kinetic…
We investigate the production of dark matter from curvature perturbations produced during inflation or in standard cosmology, for example during first order phase transitions. Perturbations break Weyl flatness of the…
We review applications of string theory to cosmology, from primordial times to the present-day accelerated expansion. Starting with a brief overview of cosmology and string compactifications, we discuss in detail moduli stabilisation,…
We study the formation of cosmic strings by confining a stochastic magnetic field into flux tubes in a numerical simulation. We use overdamped evolution in a potential that is minimized when the flux through each face in the simulation…
Production of pions in high-energy collisions with nuclei in the kinematics prohibited for free nucleons ("cumulative pions") is studied in the fusing color string model.The model describes the so-called direct mechanism for cumulative…
We consider an inflationary model inspired in the low energy limit of string theory. In this model, the scale factor grows exponentially with time. A perturbation study is performed, and we show that there is a mode which displays an…
We review recent progress in string model building in both early and late time cosmology. We describe the main theoretical and phenomenological features of an entire class of inflationary models where inflation is driven by a type IIB…
There exist several models of inflation that produce primordial bispectra that contain a large number of oscillations. In this paper we discuss these models, and aim at finding a method of detecting such bispectra in the data. We explain…