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We investigate the dynamics of single and multiple scalar fields with exponential potentials, leading to power-law and assisted inflation, in loop quantum cosmology. Unlike in the classical theory, dynamical trajectories in loop quantum…

General Relativity and Quantum Cosmology · Physics 2012-07-05 Evan Ranken , Parampreet Singh

There is a wide consensus on the correct dynamics of the background in loop quantum cosmology. In this article we make a systematic investigation of the duration of inflation by varying what we think to be the most important "unknowns" of…

General Relativity and Quantum Cosmology · Physics 2017-04-19 Killian Martineau , Aurélien Barrau , Susanne Schander

This review article aims at presenting the theory of inflation. We first describe the background spacetime behavior during the slow-roll phase and analyze how inflation ends and the Universe reheats. Then, we present the theory of…

High Energy Physics - Theory · Physics 2009-11-10 Jerome Martin

We study a class of non-local, purely gravitational models which have the correct structure to reproduce the leading infrared logarithms of quantum gravitational back-reaction during the inflationary regime. These models end inflation in a…

General Relativity and Quantum Cosmology · Physics 2014-12-05 N. C. Tsamis , R. P. Woodard

We analyze the big bounce transition of the quantum FRW model in the setting of the nonstandard loop quantum cosmology (LQC). Elementary observables are used to quantize composite observables. The spectrum of the energy density operator is…

General Relativity and Quantum Cosmology · Physics 2011-03-28 Przemyslaw Malkiewicz , Wlodzimierz Piechocki

We perform in this work an analysis of the background dynamics for $\alpha$-attractor models in the context of loop quantum cosmology. Particular attention is given to the determination of the duration of the inflationary phase that is…

General Relativity and Quantum Cosmology · Physics 2025-06-25 G. L. L. W. Levy , Rudnei O. Ramos

A phase-space approach to quantum-deformed gravity is developed. Following its reduction to an effective four-dimensional spacetime structure, we utilize it in reanalyzing the cosmic inflationary dynamics and quantum gravity. The…

General Relativity and Quantum Cosmology · Physics 2026-04-22 Swapnil Kumar Singh , Saleh O. Allehabi , Azzah A. Alshehri , Mahmoud Nasar , Abdel Nasser Tawfik

The equations for quintessential $\alpha$-attractor inflation with a single scalar field, radiation and matter in a spatially flat FLRW spacetime are recast into a regular dynamical system on a compact state space. This enables a complete…

General Relativity and Quantum Cosmology · Physics 2024-02-08 Artur Alho , Claes Uggla

Quantum gravity, as a fundamental theory of space-time, is expected to reveal how the universe may have started, perhaps during or before an inflationary epoch. It may then leave a potentially observable (but probably minuscule) trace in…

General Relativity and Quantum Cosmology · Physics 2015-12-17 Martin Bojowald

Inflation solves several cosmological problems at the classical and quantum level, with a strong agreement between the theoretical predictions of well-motivated inflationary models and observations. In this work, we study the corrections…

Quantum Physics · Physics 2021-09-08 Anirudh Gundhi , José Luis Gaona-Reyes , Matteo Carlesso , Angelo Bassi

We revisit the predictions for the duration of the inflationary phase after the bounce in loop quantum cosmology. We present our analysis for different classes of inflationary potentials that include the monomial power-law chaotic type of…

General Relativity and Quantum Cosmology · Physics 2023-02-28 L. N. Barboza , G. L. L. W. Levy , L. L. Graef , Rudnei O. Ramos

We perform a LQC-quantization of the FRW cosmological model with nonminimally coupled scalar field. Making use of a canonical transformation, we recast the theory in the minimally coupled form (Einstein frame), for which standard LQC…

General Relativity and Quantum Cosmology · Physics 2013-05-21 Michal Artymowski , Andrea Dapor , Tomasz Pawlowski

The "improved dynamics" of loop quantum cosmology is extended to include anisotropies of the Bianchi I model. As in the isotropic case, a massless scalar field serves as a relational time parameter. However, the extension is non-trivial…

General Relativity and Quantum Cosmology · Physics 2010-04-14 Abhay Ashtekar , Edward Wilson-Ewing

With a well-motivated extension of higher order holonomy corrections, the quantum theory of loop quantum cosmology (LQC) for the $k=0$ Friedmann-Robertson-Walker model (with a free massless scalar) is rigorously formulated. The analytical…

General Relativity and Quantum Cosmology · Physics 2009-08-18 Dah-Wei Chiou , Li-Fang Li

We explore the relationship between the effective dynamics in standard loop quantum cosmology (LQC) based on holonomies and triads obtained from gauge-fixing fluxes, and a modification of LQC based on holonomies and gauge-covariant fluxes…

General Relativity and Quantum Cosmology · Physics 2022-08-31 Bao-Fei Li , Parampreet Singh

Cosmological equations for homogeneous isotropic models filled by scalar fields and ultrarelativistic matter are investigated in the framework of gauge theories of gravity. Regular inflationary cosmological models of flat, closed and open…

General Relativity and Quantum Cosmology · Physics 2014-11-17 A. V. Minkevich

We compute the primordial scalar, vector and tensor metric perturbations arising from quantum field inflation. Quantum field inflation takes into account the nonperturbative quantum dynamics of the inflaton consistently coupled to the…

Astrophysics · Physics 2009-11-11 F. J. Cao

The very early universe provides the best arena we currently have to test quantum gravity theories. The success of the inflationary paradigm in accounting for the observed inhomogeneities in the cosmic microwave background already…

General Relativity and Quantum Cosmology · Physics 2015-06-15 Abhay Ashtekar

It has been widely claimed that inflation is generically eternal to the future, even in models where the inflaton potential monotonically increases away from its minimum. The idea is that quantum fluctuations allow the field to jump uphill,…

High Energy Physics - Theory · Physics 2009-11-11 Steven Gratton , Neil Turok

We derive the primordial power spectra and spectral indexes of the density fluctuations and gravitational waves in the framework of loop quantum cosmology (LQC) with holonomy and inverse-volume corrections, by using the uniform asymptotic…

General Relativity and Quantum Cosmology · Physics 2015-08-04 Tao Zhu , Anzhong Wang , Gerald Cleaver , Klaus Kirsten , Qin Sheng , Qiang Wu
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