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The k=0 Friedmann Lemaitre Robertson Walker model with a positive cosmological constant and a massless scalar field is analyzed in detail. If one uses the scalar field as relational time, new features arise already in the Hamiltonian…

General Relativity and Quantum Cosmology · Physics 2015-06-03 Tomasz Pawlowski , Abhay Ashtekar

We study the scalar modes of linear perturbations in loop quantum cosmology. This is done on a lattice where each cell is taken to be homogeneous and isotropic and can be quantized via standard homogeneous loop quantum cosmology techniques.…

General Relativity and Quantum Cosmology · Physics 2015-06-05 Edward Wilson-Ewing

Loop Quantum Cosmology strongly modifies the high-energy dynamics of Friedman-Robertson-Walker models and removes the big-bang singularity. We investigate how LQC corrections affect the stability properties of the Einstein static universe.…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Luca Parisi , Marco Bruni , Roy Maartens , Kevin Vandersloot

In this Letter, we study analytically the evolutions of the flat Friedmann-Lemaitre-Robertson-Walker (FLRW) universe and its linear perturbations in the framework of {\em the dressed metric approach} in loop quantum cosmology (LQC).…

General Relativity and Quantum Cosmology · Physics 2017-09-21 Tao Zhu , Anzhong Wang , Klaus Kirsten , Gerald Cleaver , Qin Sheng

In this paper we present an analysis of a chiral anisotropic cosmological scenario from the perspective of quintom fields. In this setup quintessence and phantom fields interact in a non-standard (chiral) way within an anisotropic Bianchi…

General Relativity and Quantum Cosmology · Physics 2023-06-16 J. Socorro , S. Pérez-Payán , Rafael Hernández-Jiménez , Abraham Espinoza-García , Luis Rey Díaz-Barrón

We extend the phenomenology of loop quantum cosmology (LQC) to second order in perturbations. Our motivation is twofold. On the one hand, since LQC predicts a cosmic bounce that takes place at the Planck scale, the second order…

General Relativity and Quantum Cosmology · Physics 2018-04-04 Ivan Agullo , Boris Bolliet , V. Sreenath

In an open Friedmann-Robertson-Walker (FRW) space background, we study the classical and quantum cosmological models in the framework of the recently proposed nonlinear massive gravity theory. Although the constraints which are present in…

General Relativity and Quantum Cosmology · Physics 2015-06-04 Babak Vakili , Nima Khosravi

The loop quantum cosmological model from ADM Hamiltonian is studied in this paper. We consider the spatially flat homogeneous FRW model. It turns out that the modified Friedmann equation keeps the same form as the APS LQC model. However,…

General Relativity and Quantum Cosmology · Physics 2022-12-27 You Ding , Xiangdong Zhang

Loop quantum cosmology (LQC) provides promising resolutions to the trans-Planckian issue and initial singularity arising in the inflationary models of general relativity. In general, due to different quantization approaches, LQC involves…

General Relativity and Quantum Cosmology · Physics 2015-12-10 Tao Zhu , Anzhong Wang , Gerald Cleaver , Klaus Kirsten , Qin Sheng , Qiang Wu

The dynamics of an inhomogeneous universe is studied with the methods of Loop Quantum Cosmology as an example of the quantization of vacuum cosmological spacetimes containing gravitational waves (Gowdy spacetimes). The analysis performed at…

General Relativity and Quantum Cosmology · Physics 2010-02-17 David Brizuela , Guillermo A. Mena Marugan , Tomasz Pawlowski

We study the implementation of Polymer Quantum Mechanics (PQM) to a system decomposed into a quasi-classical background and a small quantum subsystem, according to the original Vilenkin proposal. We develop the whole formalism in the…

General Relativity and Quantum Cosmology · Physics 2023-09-15 Eleonora Giovannetti , Giovanni Montani

We analyze the dynamics of the Bianchi I model in the presence of stiff matter, an ultrarelativistic component and a small negative cosmological constant. We quantize this model in the framework of the polymer quantum mechanics, in order to…

General Relativity and Quantum Cosmology · Physics 2018-05-16 Giovanni Montani , Andrea Marchi , Riccardo Moriconi

We study a contracting universe composed of cold dark matter and radiation, and with a positive cosmological constant. As is well known from standard cosmological perturbation theory, under the assumption of initial quantum vacuum…

General Relativity and Quantum Cosmology · Physics 2015-06-23 Yi-Fu Cai , Edward Wilson-Ewing

The success of loop quantum cosmology to resolve classical singularities of homogeneous models has led to its application to the classical Schwarszchild black hole interior, which takes the form of a homogeneous Kantowski-Sachs model. The…

General Relativity and Quantum Cosmology · Physics 2017-04-19 Jerónimo Cortez , William Cuervo , Hugo A. Morales-Técotl , Juan C. Ruelas

In loop quantum cosmology (LQC) the big bang singularity is generically resolved by a big bounce. This feature holds even when modified quantization prescriptions of the Hamiltonian constraint are used such as in mLQC-I and mLQC-II. While…

General Relativity and Quantum Cosmology · Physics 2023-06-30 Adrià Delhom , Gonzalo J. Olmo , Parampreet Singh

In this paper, we analyze the modified $f(\mathcal{R})$ gravity models in Friedmann--Lema\^{\i}tre--Robertson--Walker (FLRW) background. The actions of bouncing cosmology are studied under consideration of different viable models in…

General Relativity and Quantum Cosmology · Physics 2021-02-18 M. Ilyas , W. U. Rahman

Closed, spatially homogeneous cosmological models with a perfect fluid and a scalar field with exponential potential are investigated, using dynamical systems methods. First, we consider the closed Friedmann-Robertson-Walker models,…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Alan Coley , Martin Goliath

A specific loop quantum cosmology model, mLQC-I, motivated by Thiemann's regularization of the Hamiltonian constraint, leads to the resolution of the big bang singularity and bounce in the isotropic setting, in which either the pre-bounce…

General Relativity and Quantum Cosmology · Physics 2026-03-24 Meysam Motaharfar , Parampreet Singh

We investigate perturbations of Kantowski-Sachs models with a positive cosmological constant, using the gauge invariant 1+3 and 1+1+2 covariant splits of spacetime together with a harmonic decomposition. The perturbations are assumed to be…

General Relativity and Quantum Cosmology · Physics 2014-09-12 Zoltán Keresztes , Mats Forsberg , Michael Bradley , Peter K. S. Dunsby , László Á. Gergely

We extend the ideas introduced in the previous work to a more general space-time. In particular we consider the Kantowski-Sachs space time with space section with topology $R \times S^2$. In this way we want to study a general space time…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Leonardo Modesto