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Lattice refinement in LQC, its meaning and its necessity are discussed. The r\^ole of lattice refinement for the realisation of a successful inflationary model is explicitly shown. A simple and effective numerical technique to solve the…

General Relativity and Quantum Cosmology · Physics 2009-11-05 Mairi Sakellariadou

A general class of loop quantizations for anisotropic models is introduced and discussed, which enhances loop quantum cosmology by relevant features seen in inhomogeneous situations. The main new effect is an underlying lattice which is…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Martin Bojowald , Daniel Cartin , Gaurav Khanna

The scalar field theory of cosmological inflation constitutes nowadays one of the preferred scenarios for the physics of the early universe. In this paper we aim at studying the inflationary universe making use of a numerical lattice…

Cosmology and Nongalactic Astrophysics · Physics 2021-12-09 Angelo Caravano , Eiichiro Komatsu , Kaloian D. Lozanov , Jochen Weller

The full set of cosmological observables coming from linear scalar and tensor perturbations of loop quantum cosmology is computed in the presence of inverse-volume corrections. Background inflationary solutions are found at linear order in…

General Relativity and Quantum Cosmology · Physics 2011-03-28 Martin Bojowald , Gianluca Calcagni

In the context of loop quantum cosmology, we parametrise the lattice refinement by a parameter, $A$, and the matter Hamiltonian by a parameter, $\delta$. We then solve the Hamiltonian constraint for both a self-adjoint, and a…

General Relativity and Quantum Cosmology · Physics 2008-11-26 William Nelson , Mairi Sakellariadou

We consider curved space quantum corrections to the equations of motion of the inflaton field in the early Universe. Using the stochastic formalism in phase space, we demonstrate that the quantum corrected evolution of the inflaton can…

High Energy Physics - Phenomenology · Physics 2009-09-25 Zygmunt Lalak , Rudolf Poppe

On the one hand, inflation is an extremely convincing scenario: it solves most cosmological paradoxes and generates fluctuations that became the seeds for the growth of structures. It, however, suffers from a "naturalness" problem:…

General Relativity and Quantum Cosmology · Physics 2011-08-04 Aurelien Barrau

The evolution of a scalar field is explored taking into account the presence of a background fluid in a positively curved Universe in the framework of loop quantum cosmology. Though the mechanism that provides the initial conditions for…

Astrophysics · Physics 2009-11-13 N. J. Nunes

To avoid instabilities in the continuum semi-classical limit of loop quantum cosmology models, refinement of the underlying lattice is necessary. The lattice refinement leads to new dynamical difference equations which, in general, do not…

General Relativity and Quantum Cosmology · Physics 2008-12-18 William Nelson , Mairi Sakellariadou

Precise cosmological data from WMAP and forthcoming CMB experiments motivate the study of the quantum corrections to the slowroll inflationary parameters.We find the quantum (loop) corrections to the equations of motion of the classical…

Astrophysics · Physics 2009-11-10 D. Boyanovsky , H. J. de Vega , N. G. Sanchez

In this work we use the Loop Quantum Cosmology modified scalar-tensor reconstruction techniques in order to investigate how bouncing and inflationary cosmologies can be realized. With regard to the inflationary cosmologies, we shall be…

General Relativity and Quantum Cosmology · Physics 2018-04-18 K. Kleidis , V. K. Oikonomou

The probability of there being sufficient inflation to solve the fine-tuning associated with the horizon and flatness problems has recently been shown to be exponentially small, within the context of classical general relativity. Here this…

General Relativity and Quantum Cosmology · Physics 2007-08-27 William Nelson

We develop a consistent analytic approach to determine the conditions under which slow roll inflation can arise when the inflaton is the same scalar field that is responsible for the bounce in Loop Quantum Cosmology (LQC). We find that the…

General Relativity and Quantum Cosmology · Physics 2019-11-04 Anshuman Bhardwaj , Edmund J. Copeland , Jorma Louko

Attention has been recently drawn towards models in which inflation and quintessence schemes are unified. In such `quintessential inflation' models, a unique scalar field is required to play both the role of the inflaton and of the…

High Energy Physics - Phenomenology · Physics 2016-09-06 Marco Peloso , Francesca Rosati

Inflation is often described through the dynamics of a scalar field, slow-rolling in a suitable potential. Ultimately, this inflaton must be identified as the expectation value of a quantum field, evolving in a quantum effective potential.…

High Energy Physics - Phenomenology · Physics 2021-05-11 Jens O. Andersen , Magdalena Eriksson , Anders Tranberg

Inflationary cosmology attempts to provide a natural explanation for the flatness and homogeneity of the observable universe. In the context of reversible (unitary) evolution, this goal is difficult to satisfy, as Liouville's theorem…

High Energy Physics - Theory · Physics 2010-07-09 Sean M. Carroll , Heywood Tam

Loop quantum cosmology provides an efficient framework to study the evolution of the Universe beyond the classical Big Bang paradigm. Because of holonomy corrections, the singularity is replaced by a "bounce". The dynamics of the background…

General Relativity and Quantum Cosmology · Physics 2015-03-13 Jakub Mielczarek , Thomas Cailleteau , Julien Grain , Aurelien Barrau

In the first part of this paper, we outline the construction of an inflationary cosmology in the framework where inflation is described by a universally evolving scalar field, with the Lagrangian ${\cal L}_\phi=-{1/2}(\partial\phi)^2…

Astrophysics · Physics 2009-12-15 Ishwaree P. Neupane , Christoph Scherer

In this work we construct a bottom-up reconstruction technique for Loop Quantum Cosmology scalar-tensor theories, from the observational indices. Particularly, the reconstruction technique is based on fixing the functional form of the…

General Relativity and Quantum Cosmology · Physics 2018-05-02 Jaume de Haro , S. D. Odintsov , V. K. Oikonomou

This thesis is centered on three main subjects within the theory of inflation and cosmological perturbations: loop corrections to the power spectrum of curvature fluctuations generated during inflation; evolution of cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2010-04-13 Emanuela Dimastrogiovanni
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