Related papers: Power Spectrum with Auxiliary Fields in de Sitter …
The spectrum of primordial fluctuations from inflation can be obtained using a mathematically controlled, and systematically extendable, uniform approximation. Closed-form expressions for power spectra and spectral indices may be found…
We study the implications of deformed quantum algebras for the generation of primordial perturbations from slow-roll inflation. Specifically, we assume that the quantum commutator of the inflaton's amplitude and momentum in Fourier space…
We present some features of early universe cosmology in terms of Hankel functions index ($\nu$). Actually, the recent data from observational cosmology indicate that our universe was nearly de Sitter space-time in the early times which…
We study the classical radiation emitted by free-falling charges in de Sitter spacetime coupled to different kinds of fields. Specifically we consider the cases of the electromagnetic field, linearized gravity and scalar fields with…
The purpose of this work is to use a renormalized quantum scalar field to investigate very early cosmology, in the Planck era immediately following the big bang. Renormalization effects make the field potential dependent on length scale,…
We consider a model of the early universe which consists of two scalar fields: the inflaton, and a second field which drives the stabilisation of the Planck mass (or gravitational constant). We show that the non-minimal coupling of this…
We study the correction to the scale invariant power spectrum of a scalar field on de Sitter space from small black holes that formed during a pre-inflationary matter dominated era. The formation probability of such black holes is estimated…
We introduce a second-order stochastic effective theory for light scalar fields in de Sitter spacetime, extending the validity of the stochastic approach beyond the massless limit and demonstrating how it can be used to compute…
We compute the one- and two-loop corrected mode function of a massless minimally coupled scalar endowed with a quartic self-interaction in the locally de Sitter background of an inflating universe for a state which is released in…
We investigate a set of cosmological models for which the primordial power spectrum has a large-scale power deficit. The standard power-law spectrum is subject to long-wavelength modifications described by some new parameters, resulting in…
The vacuum inflation with a boundary condition specified at a short-distance scale in a generally primeval non-flat Universe, and implications of the correspondingly modified primordial power spectrum via the WMAP data are investigated. We…
We consider the role of the zero-point energy of a quantum field in cosmology and show that the flow of trans-planckian momenta due to redshift acts as a source for this energy, regularized with a cut-off Lambda in physical momenta. In…
Approximate de Sitter symmetry of inflating Universe is responsible for the approximate flatness of the power spectrum of scalar perturbations. However, this is not the only option. Another symmetry which can explain nearly scale-invariant…
We start with the consideration of the loop effects for light fields with non-zero mass in the expanding Poincar\'e patch of de Sitter space-time. We derive the Dyson-Schwinger equation, which sums up the leading infrared (growing with…
A crucial issue in cosmology is the determination of the fluctuation power spectrum.The standard picture of the matter clustering, the Cold Dark Matter model (and its variant), assumes that,on scales smaller than a certain ``flattening…
Modifications to the primordial power spectrum of inflationary density perturbations have been studied recently using a boundary effective field theory approach. In the approximation of a fluctuating quantum field on a fixed background, the…
The stochastic effective theory approach, often called stochastic inflation, is widely used in cosmology to describe scalar field dynamics during inflation. The existing formulations are, however, more qualitative than quantitative because…
I study a semiclassical approach to warm inflation scenario introduced in previous works. In this work, I define the fluctuations for the matter field by means of a new coarse - grained field with a suppression factor G. This field…
In this work we explore the possibility of variations in the primordial scalar power spectrum around the power-law shape, as predicted by single-field slow-roll inflationary scenarios. We search for the trace of these fluctuations in a…
An investigation is undertaken into the properties and effects of a preinflationary era during at least part of which semiclassical gravity was valid. It is argued that if the Universe (or our part of it) was approximately homogeneous and…