相关论文: Density Perturbations in the Universe from Massive…

If the universe had a large curvature before inflation there is a deviation from the scale invariant perturbations of the inflaton at the beginning of inflation. This may have some effect on the CMB anisotropy at large angular scales. We…

We propose that cosmological density perturbation may originate from passive fluctuations of the inflaton, which are induced by colored quantum noise due to the coupling of the inflaton to the quantum environment. At small scales, the…

In a class of non-singular cosmologies derived from higher-order corrections to the low-energy bosonic string action, we derive evolution equations for the most general cosmological scalar, vector and tensor perturbations. In the large…

The \delta N formalism is extended to include the perturbation of the vector field. The latter is quantized in de Sitter space-time and it is found that in general the particle production process of the vector field is anisotropic. This…

The large-scale structure in the Universe is believed to arise out of small random density perturbations generated in the very early Universe, that are amplified by gravity. Large and usually intricate N-body simulations are typically…

Vector fields in the expanding Universe are considered within the multidimensional theory of General Relativity. Vector fields in general relativity form a three-parametric variety. Our consideration includes the fields with a nonzero…

The spectrum of cosmological perturbations in the context of the one-bubble open inflation model is discussed, taking into account fluctuations of the metric. We find that, quite generically,thin wall single field models have no…

We study the properties of cosmological density perturbations in a multi-component system consisting of a scalar field and a perfect fluid. We discuss the number of degrees of freedom completely describing the system, introduce a full set…

We present a gauge invariant formalism to study the evolution of curvature perturbations during decay of the inflaton or some other field that dominates the energy density. We specialize to the case where the total curvature perturbation…

Perturbations in cosmic microwave background (CMB) photons and large scale structure of the universe are sourced primarily by the curvature perturbation which is widely believed to be produced during inflation. In this paper we present a…

In effective supergravity theories following from the superstring, a modulus field can quite naturally set the neccessary initial conditions for successful cosmological inflation to be driven by a hidden sector scalar field. The leading…

Power suppression of the cosmic microwave background on the largest observable scales could provide valuable clues about the particle physics underlying inflation. Here we consider the prospect of power suppression in the context of the…

The incorporation of bulk viscosity process to General Relativity leads to the appearance of nonsingular backgrounds that, at early and late times, depict an accelerated universe. These backgrounds could be analytically calculated and…

Topological defects may play the role of the curvatons. We propose a new mechanism of generating density perturbations from cosmological defects in inflationary models. We show several examples in which defects play crucial role in…

We propose a new source for the cosmological density perturbation which is passive fluctuations of the inflaton driven dynamically by a colored quantum noise as a result of its coupling to other massive quantum fields. The created…

Motivated by the interest in models of the early universe where statistical isotropy is broken and can be revealed in cosmological observations, we consider an SU(2) theory of gauge interactions in a single scalar field inflationary…

We consider the presence and evolution of primordial density perturbations in a cosmological model based on a simple ansatz which captures -- by providing a set of effective gravitational field equations -- the strength of the enhanced…

A model of the Universe as a mixture of a scalar (inflaton or rolling tachyon from the string theory) and a matter field (classical particles) is analyzed. The particles are created at the expense of the gravitational energy through an…

We introduce a new method for calculating density perturbations in hybrid inflation which avoids treating the fluctuations of the "waterfall" field as if they were small perturbations about a classical trajectory. We quantize only the…

Fundamental formulae representing the density perturbation spectrums generated in inflationary scenarios are rigorously proved. Quantum fluctuations as initial conditions for structure generation in some inflationary era can be calculated…