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We study the dynamics of gauge-invariant scalar perturbations in cosmological scenarios with a modified Friedmann equation, such as quantum gravity bouncing cosmologies. We work within a separate universe approximation which captures…

General Relativity and Quantum Cosmology · Physics 2023-03-02 Steffen Gielen , Lisa Mickel

We apply a singularity resolution technique utilized in loop quantum gravity to the polymer representation of quantum mechanics on R with the singular -1/|x| potential. On an equispaced lattice, the resulting eigenvalue problem is identical…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Viqar Husain , Jorma Louko , Oliver Winkler

Using effective dynamics, we investigate the behavior of expansion and shear scalars in different proposed quantizations of the Kantowski-Sachs spacetime with matter in loop quantum cosmology. We find that out of the various proposed…

General Relativity and Quantum Cosmology · Physics 2015-01-08 Anton Joe , Parampreet Singh

The canonical approach to Riemannian quantum gravity is reviewed with reference to local supersymmetry, to the classical boundary-value problem arising from the Hartle-Hawking quantum state, and particularly for (anti-)self-dual geometries.…

General Relativity and Quantum Cosmology · Physics 2007-05-23 P. D. D'Eath

We use the mathematical framework of loop quantum gravity (LQG) to study the quantization of three dimensional (Riemannian) gravity with positive cosmological constant (Lambda>0). We show that the usual regularization techniques (successful…

General Relativity and Quantum Cosmology · Physics 2014-11-20 Alejandro Perez , Daniele Pranzetti

We elaborate on the Ashtekar's formalism for spherically symmetric midisuperspaces and, for loop quantization, propound a new quantization scheme which yields a graph-preserving Hamiltonian constraint operator and by which one can impose…

General Relativity and Quantum Cosmology · Physics 2013-01-28 Dah-Wei Chiou , Wei-Tou Ni , Alf Tang

Instead of assuming that they depend only on the background variables, we investigate the hypothesis that counter-terms appearing in the deformed algebra approach to loop quantum cosmology depend on the full phase-space variables. We derive…

General Relativity and Quantum Cosmology · Physics 2025-10-28 Maxime De Sousa , Aurélien Barrau , Killian Martineau

We use Dirac's method for the quantization of constrained systems in order to quantize a spatially flat Friedmann-Lema\^{i}tre-Robertson-Walker spacetime in the context of $f(Q)$ cosmology. When the coincident gauge is considered, the…

General Relativity and Quantum Cosmology · Physics 2021-10-22 N. Dimakis , A. Paliathanasis , T. Christodoulakis

Loop quantum gravity corrections, in the presence of inhomogeneities, can lead to a deformed constraint algebra. Such a deformation implies that the effective theory is no longer generally covariant. As a consequence, the geometrical…

General Relativity and Quantum Cosmology · Physics 2015-06-17 Rakesh Tibrewala

We apply the nonstandard loop quantum cosmology method to quantize a flat Friedmann-Robertson-Walker cosmological model with a free scalar field and the cosmological constant $\Lambda>0$. Modification of the Hamiltonian in terms of loop…

General Relativity and Quantum Cosmology · Physics 2011-05-12 Jakub Mielczarek , Wlodzimierz Piechocki

Generally, quantum field theories can be thought as deformations away from conformal field theories. In this article, with a simple bottom up model assumed to possess a holographic description, we study a putative large N quantum field…

High Energy Physics - Theory · Physics 2018-08-01 Avik Banerjee , Arnab Kundu , Augniva Ray

The use of non-regular representations of the Heisenberg-Weyl commutation relations has proved to be useful for studying conceptual and technical issues in quantum gravity. Of particular relevance is the study of Loop Quantum Cosmology…

General Relativity and Quantum Cosmology · Physics 2011-04-11 Alejandro Corichi , Tatjana Vukasinac , Jose A. Zapata

Open FRW model in Loop Quantum Cosmology is under consideration. The left and right invariant vector fields and holonomies along them are studied. It is shown that in the hyperbolic geometry of $k=-1$ it is possible to construct a suitable…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Lukasz Szulc

Quantum groups and non-commutative spaces have been repeatedly utilized in approaches to quantum gravity. They provide a mathematically elegant cut-off, often interpreted as related to the Planck-scale quantum uncertainty in position. We…

General Relativity and Quantum Cosmology · Physics 2011-08-09 Eugenio Bianchi , Carlo Rovelli

A simple idea of relating the LQG and LQC degrees of freedom is discussed in context of toroidal Bianchi I model. The idea is an expansion of the construction originally introduced by Ashtekar and Wilson-Ewing and relies on explicit…

General Relativity and Quantum Cosmology · Physics 2015-12-16 Tomasz Pawłowski

Within the framework of loop quantum cosmology, there exists a semi-classical regime where spacetime may be approximated in terms of a continuous manifold, but where the standard Friedmann equations of classical Einstein gravity receive…

General Relativity and Quantum Cosmology · Physics 2009-11-10 James E. Lidsey

We analyze the effective dynamics of a polymer quantized homogeneous and anisotropic Bianchi-I universe coupled to a polymer quantized scalar field. We use a pressureless dust field as an internal clock, and work with the gravitational…

General Relativity and Quantum Cosmology · Physics 2025-09-30 Aleena Zulfiqar , Syed Moeez Hassan

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

The phenomenology for the deep spatial geometry of loop quantum gravity is discussed. In the context of a simple model of an atom of space, it is shown how purely combinatorial structures can affect observations. The angle operator is used…

General Relativity and Quantum Cosmology · Physics 2015-06-03 Seth A. Major

In this paper we study the effect of a torus topology on Loop Quantum Cosmology. We first derive the Teichmueller space parametrizing all possible tori using Thurston's theorem and construct a Hamiltonian describing the dynamics of these…

General Relativity and Quantum Cosmology · Physics 2009-09-15 Raphael Lamon