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We study oscillatory universes within the context of Loop Quantum Cosmology. We make a comparative study of flat and positively curved universes sourced by scalar fields with either positive or negative potentials. We investigate how…

General Relativity and Quantum Cosmology · Physics 2009-11-10 D. J. Mulryne , N. J. Nunes , R. Tavakol , J. E. Lidsey

General relativity and its cosmological solution predicts the existence of tensor modes of perturbations evolving on top of our Friedman-Lema\^itre-Robertson-Walker expanding Universe. Being gauge invariant and not necessarily coupled to…

General Relativity and Quantum Cosmology · Physics 2023-01-20 Amaury Micheli , Patrick Peter

In a class of generalized gravity theories with general couplings between the scalar field and the scalar curvature in the Lagrangian, we can describe the quantum generation and the classical evolution of both the scalar and tensor…

General Relativity and Quantum Cosmology · Physics 2015-06-25 J. Hwang

Effects from nonstandard corrections to Newtonian gravity, at large scale, can be investigated using the cosmological structure formation. In particular, it is possible to show if and how a logarithmic correction (as that induced from…

General Relativity and Quantum Cosmology · Physics 2021-07-29 Salvatore Capozziello , Mir Faizal , Mir Hameeda , Behnam Pourhassan , Vincenzo Salzano

We discuss how a cyclic model for the flat universe can be constructively derived from Loop Quantum Gravity. This model has a lower bounce, at small values of the scale factor, which shares many similarities with that of Loop Quantum…

General Relativity and Quantum Cosmology · Physics 2017-06-13 Francesco Cianfrani , Jerzy Kowalski-Glikman , Giacomo Rosati

A simple model is constructed which allows to compute modified dispersion relations with effects from loop quantum gravity. Different quantization choices can be realized and their effects on the order of corrections studied explicitly. A…

General Relativity and Quantum Cosmology · Physics 2016-08-31 Martin Bojowald , Hugo A. Morales-Tecotl , Hanno Sahlmann

We present results for the cosmic non-linear density-fluctuation power spectrum based on the analytical formalism developed in [1] which allows us to study cosmic structure formation based on Newtonian particle dynamics in phase-space. This…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-22 Tristan Daus , Elena Kozlikin

It is known than the inclusion of spatial curvature can modify the evolution of matter perturbations and affect the Large Scale Structure (LSS) formation. We quantify the effects of the non-zero space curvature in terms of LSS formation for…

General Relativity and Quantum Cosmology · Physics 2020-12-08 Jhonny A. Agudelo Ruiz , Júlio C. Fabris , Alan M. Velasquez-Toribio , Ilya L. Shapiro

A semiclassical description of quantum systems is applied to probe the dynamics of the cosmological model of an inflationary universe with quadratic inflaton potential, described in a quantum framework of geometrodynamics. The systematic…

General Relativity and Quantum Cosmology · Physics 2022-10-27 David Brizuela , Tomasz Pawlowski

The degrees of quantum coherence of cosmological perturbations of different spins are computed in the large-scale limit and compared with the standard results holding for a single mode of the electromagnetic field in an optical cavity. The…

General Relativity and Quantum Cosmology · Physics 2017-11-09 Massimo Giovannini

We show how to reliably calculate quantum gravitational corrections to cosmological models using the unique effective action formalism for quantum gravity. Our calculations are model independent and apply to any ultra-violet complete theory…

High Energy Physics - Theory · Physics 2025-01-07 Xavier Calmet , Roberto Casadio , Marco Sebastianutti

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

We show how Loop Quantum Cosmology can be derived as an effective semiclassical description of Loop Quantum Gravity. Using the tools of QRLG, a gauge fixed version of LQG, we take the coherent states of the fundamental microscopic theory…

General Relativity and Quantum Cosmology · Physics 2014-10-20 Emanuele Alesci , Francesco Cianfrani

We study linear cosmological perturbations in a previously introduced family of deformations of general relativity characterized by the absence of new degrees of freedom. The homogeneous and isotropic background in this class of theories is…

General Relativity and Quantum Cosmology · Physics 2010-06-08 Kirill Krasnov , Yuri Shtanov

In the context of f(R) theories of gravity, we study the cosmological evolution of scalar perturbations by using a completely general procedure. We find that the exact fourth-order differential equation for the matter density perturbations…

Astrophysics · Physics 2015-05-13 A. de la Cruz-Dombriz , A. Dobado , A. L. Maroto

We study the quantum-gravitational corrections to the power spectrum of a gauge-invariant inflationary scalar perturbations in a closed model of a universe. We consider canonical quantum gravity as an approach to quantizing gravity. This…

General Relativity and Quantum Cosmology · Physics 2023-02-15 Tatevik Vardanyan , Claus Kiefer

We discuss predictions for cosmology which result from the scaling solution of functional flow equations for a quantum field theory of gravity. A scaling solution is necessary to render quantum gravity renormalizable. Our scaling solution…

General Relativity and Quantum Cosmology · Physics 2023-01-13 C. Wetterich

The universal character of the gravitational interaction provided by the equivalence principle motivates a geometrical description of gravity. The standard formulation of General Relativity \`a la Einstein attributes gravity to the…

General Relativity and Quantum Cosmology · Physics 2021-04-13 Jose Beltrán Jiménez , Lavinia Heisenberg , Tomi Sebastian Koivisto , Simon Pekar

The spatially flat and isotropic cosmological model of Brans-Dicke theory with coupling parameter $\omega\neq-3/2$ is quantized by the approach of loop quantum cosmology. An interesting feature of this model is that, although the…

General Relativity and Quantum Cosmology · Physics 2013-04-16 Xiangdong Zhang , Michal Artymowski , Yongge Ma

We consider a new variant of cosmological perturbation theory that has been designed specifically to include non-linear density contrasts on scales 100 Mpc, while still allowing for linear fluctuations on larger scales. This theory is used…

General Relativity and Quantum Cosmology · Physics 2019-04-08 Christopher S. Gallagher , Timothy Clifton
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