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Quantum cosmology is traditionally formulated in a minisuperspace setting, implicitly averaging fields over space to obtain homogeneous models. For universal reasons related to the uncertainty principle, quantum corrections then depend on…

General Relativity and Quantum Cosmology · Physics 2019-06-05 Martin Bojowald

Loop quantum cosmology (LQC) is used to provide concrete evidence in support of the general paradigm underlying spin foam models (SFMs). Specifically, it is shown that: i) the physical inner product in the timeless framework equals the…

General Relativity and Quantum Cosmology · Physics 2009-12-10 Abhay Ashtekar , Miguel Campiglia , Adam Henderson

The framework of quantum symmetry reduction is applied to loop quantum gravity with respect to transitively acting symmetry groups. This allows to test loop quantum gravity in a large class of minisuperspaces and to investigate its features…

General Relativity and Quantum Cosmology · Physics 2010-11-19 Martin Bojowald

We describe quantization schemes for scalar field cosmology in the metric variables with fundamental discreteness imposed with a lattice. The variables chosen for quantization determine the lattice, and each lattice produces distinct…

General Relativity and Quantum Cosmology · Physics 2025-07-18 Mustafa Saeed , Viqar Husain

We study the classical and quantum cosmology of a $(4+d)$-dimensional spacetime minimally coupled to a scalar field and present exact solutions for the resulting field equations for the case where the universe is spatially flat. These…

High Energy Physics - Theory · Physics 2009-11-10 S. Jalalzadeh , F. Ahmadi , H. R. Sepangi

Considering as usual that the underlying geometry of our universe is well described by the spatially flat Friedmann-Lemaitre-Robertson-Walker line element, we review how the background of holonomy corrected Loop Quantum Cosmology (LQC)…

General Relativity and Quantum Cosmology · Physics 2019-05-01 Jaume de Haro , Llibert Aresté Saló , Supriya Pan

We construct and study Loop Quantum Cosmology (LQC) when the Barbero-Immirzi parameter takes the complex value $\gamma=\pm i$. We refer to this new quantum cosmology as complex Loop Quantum Cosmology. We proceed in making an analytic…

General Relativity and Quantum Cosmology · Physics 2015-06-22 Jibril Ben Achour , Julien Grain , Karim Noui

The closed, k=1, FRW model coupled to a massless scalar field is investigated in the framework of loop quantum cosmology using analytical and numerical methods. As in the k=0 case, the scalar field can be again used as emergent time to…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Abhay Ashtekar , Tomasz Pawlowski , Parampreet Singh , Kevin Vandersloot

The Wheeler-DeWitt equation is obtained for Kasner-like cosmologies. Some solutions to this equation are presented for empty space, space filled with a cosmological constant and in the presence of a scalar field. We also briefly discuss a…

High Energy Physics - Theory · Physics 2007-05-23 M. Maceda

We consider the k=1 Friedman-Lemaitre-Robertson-Walker (FLRW) model within loop quantum cosmology (LQC), from the perspective of the two available quantization prescriptions. We focus our attention on the existence of the so called `inverse…

General Relativity and Quantum Cosmology · Physics 2016-04-28 Alejandro Corichi , Asieh Karami

Loop quantum cosmology is a symmetry reduced quantization of cosmological spacetimes based on loop quantum gravity. While it has been successful in resolution of various cosmological singularities and connecting Planck scale physics to…

General Relativity and Quantum Cosmology · Physics 2019-12-25 Klaus Liegener , Parampreet Singh

We study the dynamics of the scalar modes of linear perturbations around a flat, homogeneous and isotropic background in loop quantum cosmology. The equations of motion include quantum geometry effects and hold at all curvature scales so…

General Relativity and Quantum Cosmology · Physics 2015-05-30 Edward Wilson-Ewing

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, such as the quantum bounce and…

General Relativity and Quantum Cosmology · Physics 2009-04-28 Jinsong Yang , You Ding , Yongge Ma

Loop Quantum Cosmology adapts the techniques of Loop Quantum Gravity in the quantization of homogeneous cosmological models obtained from General Relativity by symmetry reduction. As a necessary step towards the extraction of realistic…

General Relativity and Quantum Cosmology · Physics 2011-09-27 Mercedes Martín-Benito

Loop quantum cosmological methods are extended to homogeneous models in diagonalized form. It is shown that the diagonalization leads to a simplification of the volume operator such that its spectrum can be determined explicitly. This…

General Relativity and Quantum Cosmology · Physics 2011-05-05 Martin Bojowald

We continue our analysis of a quantum cosmology model describing a flat Friedmann--Lema\^itre--Robertson--Walker universe filled with a (free) massless scalar field and an arbitrary perfect fluid. For positive energy density in the scalar…

General Relativity and Quantum Cosmology · Physics 2022-04-08 Steffen Gielen , Lucía Menéndez-Pidal

We present a rigorous formulation of the Quantum Big Bounce for the closed isotropic Universe, filled with a self-interacting scalar field, that emerges from the interaction with an ekpyrotic potential. Working in a covariant approach to…

General Relativity and Quantum Cosmology · Physics 2026-03-09 S. Lo Franco , G. Montani

We have studied various classical solutions in $R^2$ cosmology. Especially we have obtained general classical solutions in pure $R^2$\ cosmology. Even in the quantum theory, we can solve the Wheeler-DeWitt equation in pure $R^2$\ cosmology…

General Relativity and Quantum Cosmology · Physics 2009-10-28 M. Kenmoku , K. Otsuki , K. Shigemoto , K. Uehara

The existence of a quantum bounce in isotropic spacetimes is a key result in loop quantum cosmology (LQC), which has been demonstrated to arise in all the models studied so far. In most of the models, the bounce has been studied using…

General Relativity and Quantum Cosmology · Physics 2017-06-20 Peter Diener , Brajesh Gupt , Parampreet Singh

A model for a flat isotropic universe with a negative cosmological constant $\Lambda$ and a massless scalar field as sole matter content is studied within the framework of Loop Quantum Cosmology. By application of the methods introduced for…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Eloisa Bentivegna , Tomasz Pawlowski