Related papers: Modified dispersion relations, inflation and scale…
Light scalar and pseudoscalar particles are compelling dark matter candidates, with a vast running experimental program to discover them. Previous studies have shown that these light fields can generate sizable isocurvature perturbations in…
Non-commutativity of spacetime at the Planck scale may deform the usual dispersion relations. And these deformed dispersion relations could lead to the accelerating phase without a scalar field. In this paper, we have calculated the…
We study cosmological tensor perturbations induced by second-order scalar perturbations in the presence of anisotropic non-Gaussianity. This class of induced tensor modes arises on superhorizon scales through the intrinsic quadrupole…
We study the scalar modes that, being observable today, were trans-Planckian before inflation, within the context of hybrid Loop Quantum Cosmology (LQC). We analyse the dynamics of these highly ultraviolet modes by introducing modified…
Slow-roll inflation can become eternal if the quantum variance of the inflaton field around its slowly rolling classical trajectory is converted into a distribution of classical spacetimes inflating at different rates, and if the variance…
We show that scale-scale correlations are a generic feature of slow-roll inflation theories. These correlations result from the long-time tails characteristic of the time dependent correlations because the long wavelength density…
We show that the difference between the theoretically expected and measured by WMAP amplitude of the quadrupole fluctuations of CMB can be related to the impact of the anisotropic curvature of the homogeneous universe dominated by the dark…
The Wilkinson Microwave Anisotropy Probe microwave background data suggest that the primordial spectrum of scalar curvature fluctuations is suppressed at small wavenumbers. We propose a UV/IR mixing effect in small-field inflationary models…
Recently, it has been found that complete resolution of the Hubble tension might point to a scale-invariant Harrison-Zeldovich spectrum of primordial scalar perturbation, i.e. $n_s=1$ for $H_0\sim 73$km/s/Mpc. We show that for well-known…
We calculate the impact of quantum gravity-motivated ultraviolet cutoffs on inflationary predictions for the cosmic microwave background spectrum. We model the ultraviolet cutoffs fully covariantly to avoid possible artifacts of covariance…
Cosmological inflation is the dominating paradigm to account for observations of the Cosmic Microwave Background (CMB). In this thesis, we study the phenomenology of a class of particularly well motivated models of inflation, known under…
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…
We re-examine a recently proposed scenario where the deformed dispersion relations associated with a flow of the spectral dimension to a UV value of 2 leads to a scale-invariant spectrum of cosmological fluctuations, without the need for…
The possibility of thermally induced initial density perturbations in inflationary cosmology is examined. The fluctuation dynamics of a scalar field plus thermal bath system during slow roll is described by a Langevin-like equation.…
Coupling between sub- and super-Hubble modes can affect the locally observed statistics of our universe. In the context of Quasi-Single Field Inflation, we can compute correlation functions and derive the influence of those unobservable…
We study the effect that quantum fluctuations produced during the nucleation of a single-bubble open inflationary universe have on the amplitude of temperature anisotropies in the microwave background. We compute the instanton action for…
Using a large N sigma model approximation we explicitly calculate the power spectrum of gravitational waves arising from a global phase transition in the early universe and we confirm that it is scale invariant, implying an observation of…
In Schroedinger picture we study the possible effects of trans-Planckian physics on the quantum evolution of massive non-minimally coupled scalar field in de Sitter space. For the nonlinear Corley-Jacobson type dispersion relations with…
In a recent paper [17], we studied the evolution of the background geometry and scalar perturbations in an inflationary, spatially closed Friedmann-Lema\^itre-Robertson-Walker (FLRW) model having constant positive spatial curvature and…
It is investigated if predictions of the inflationary scenario regarding spectra of scalar and tensor perturbations generated from quantum vacuum fluctuations are robust with respect to a modification of the dispersion law for frequencies…