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The Immirzi parameter is promoted to be a scalar field and the Hamiltonian analysis of the corresponding dynamical system is performed in the presence of gravity. We identified some SU(2) connections, generalizing Ashtekar-Barbero…

General Relativity and Quantum Cosmology · Physics 2016-09-14 Flavio Bombacigno , Francesco Cianfrani , Giovanni Montani

A quantum cosmological model with radiation and a dilaton scalar field is analysed. The Wheeler-deWitt equation in the mini-superspace induces a Schr\"odinger equation, which can be solved. An explicit wavepacket is constructed for a…

General Relativity and Quantum Cosmology · Physics 2015-06-11 J. C. Fabris , F. T. Falciano , P. Vargas Moniz , J. Marto , N. Pinto-Neto

Determining the physical Hilbert space is often considered the most difficult but crucial part of completing the quantization of a constrained system. In such a situation it can be more economical to use effective constraint methods, which…

Mathematical Physics · Physics 2009-12-04 Martin Bojowald , Artur Tsobanjan

We are concerned with the issue of quantization of a scalar field in a diffeomorphism invariant manner. We apply the method used in Loop Quantum Gravity. It relies on the specific choice of scalar field variables referred to as the polymer…

General Relativity and Quantum Cosmology · Physics 2009-11-11 W. Kaminski , J. Lewandowski , A. Okolow

Several examples are known where quantum gravity effects resolve the classical big bang singularity by a bounce. The most detailed analysis has probably occurred for loop quantum cosmology of isotropic models sourced by a free, massless…

General Relativity and Quantum Cosmology · Physics 2008-12-18 Martin Bojowald

In this paper it is studied the cosmology of a homogeneous and isotropic spacetime endorsed with a conformally coupled massless scalar field. We find six different solutions of the Friedmann equation that represent six different types of…

General Relativity and Quantum Cosmology · Physics 2017-09-20 Salvador J. Robles-Perez

Loop quantum cosmology homogeneous models with a massless scalar field show that the big-bang singularity can be replaced by a big quantum bounce. To gain further insight on the nature of this bounce, we study the semi-discrete loop quantum…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Pablo Laguna

We present the method of describing an evolution in quantum cosmology in the framework of the reduced phase space quantization of loop cosmology. We apply our method to the flat Friedman-Robertson-Walker model coupled to a massless scalar…

General Relativity and Quantum Cosmology · Physics 2012-03-06 Jakub Mielczarek , Wlodzimierz Piechocki

In quantum cosmology, one applies quantum physics to the whole universe. While no unique version and no completely well-defined theory is available yet, the framework gives rise to interesting conceptual, mathematical and physical…

General Relativity and Quantum Cosmology · Physics 2015-01-21 Martin Bojowald

Since there are quantization ambiguities in constructing the Hamiltonian constraint operator in isotropic loop quantum cosmology, it is crucial to check whether the key features of loop quantum cosmology are robust against the ambiguities.…

General Relativity and Quantum Cosmology · Physics 2010-04-14 Jinsong Yang , You Ding , Yongge Ma

The global dynamics of a homogeneous universe in Loop Quantum Cosmology is viewed as a scattering process of its geometrodynamical equivalent. This picture is applied to build a flexible (easy to generalize) and not restricted just to…

General Relativity and Quantum Cosmology · Physics 2010-04-22 Wojciech Kaminski , Tomasz Pawlowski

The detailed formulation for loop quantum cosmology (LQC) in the Bianchi I model with a massless scalar field was recently constructed. In this paper, its effective dynamics with the LQC discreteness corrections is studied and the equations…

General Relativity and Quantum Cosmology · Physics 2007-09-12 Dah-Wei Chiou

Quantum field theory in curved spacetimes suffers in general from an infinite ambiguity in the choice of Fock representation and associated vacuum. In cosmological backgrounds, the requirement of a unitary implementation of the field…

High Energy Physics - Theory · Physics 2020-04-20 Luis J. Garay , Alberto García Martín-Caro , Mercedes Martín-Benito

The goal of spin foam models is to provide a viable path integral formulation of quantum gravity. Because of background independence, their underlying framework has certain novel features that are not shared by path integral formulations of…

General Relativity and Quantum Cosmology · Physics 2011-01-25 Abhay Ashtekar , Miguel Campiglia , Adam Henderson

The flat, homogeneous, and isotropic universe with a massless scalar field is a paradigmatic model in Loop Quantum Cosmology. In spite of the prominent role that the model has played in the development of this branch of physics, there still…

General Relativity and Quantum Cosmology · Physics 2010-09-23 Mercedes Martin-Benito , Guillermo A. Mena Marugan , Javier Olmedo

Homogeneous cosmological models with non-vanishing intrinsic curvature require a special treatment when they are quantized with loop quantum cosmological methods. Guidance from the full theory which is lost in this context can be replaced…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Martin Bojowald , Ghanashyam Date , Kevin Vandersloot

We study the quantum cosmology of a flat Friedmann-Lema\^{i}tre-Robertson-Walker universe filled with a (free) massless scalar field and a perfect fluid that represents radiation or a cosmological constant whose value is not fixed by the…

General Relativity and Quantum Cosmology · Physics 2020-10-01 Steffen Gielen , Lucía Menéndez-Pidal

The Lorentzian Hamiltonian constraint is solved for isotropic loop quantum cosmology coupled to a massless scalar field. As in the Euclidean case, the discreteness of quantum geometry removes the classical singularity from the quantum…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Franz Hinterleitner , Seth Major

We make the cosmological constant, {\Lambda}, into a field and restrict the variations of the action with respect to it by causality. This creates an additional Einstein constraint equation. It restricts the solutions of the standard…

General Relativity and Quantum Cosmology · Physics 2015-05-28 John D. Barrow , Douglas J. Shaw

The cosmological scale factor $a(t)$ of the flat-space Robertson-Walker geometry is examined from a Hamiltonian perspective wherein $a(t)$ is interpreted as an independent dynamical coordinate and the curvature density $\sqrt {- g(a)}…

General Physics · Physics 2008-10-04 M. Ibison
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