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We re-examine the process of loop quantization for flat isotropic models in cosmology. In particular, we contrast different inequivalent `loop quantizations' of these simple models through their respective successes and limitations and…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Alejandro Corichi , Parampreet Singh

This Chapter provides an up to date, pedagogical review of some of the most relevant advances in loop quantum cosmology. We review the quantization of homogeneous cosmological models, their singularity resolution and the formulation of…

General Relativity and Quantum Cosmology · Physics 2015-06-15 Ivan Agullo , Alejandro Corichi

We consider one-loop corrections to the bispectrum and skewness of cosmological density fluctuations induced by gravitational evolution. As has been established by comparison with numerical simulations, tree-level perturbation theory (PT)…

Astrophysics · Physics 2009-10-28 Roman Scoccimarro

It is generally expected that in a non-singular cosmological model a cyclic evolution is straightforward to obtain on introduction of a suitable choice of a scalar field with a negative potential or a negative cosmological constant which…

General Relativity and Quantum Cosmology · Physics 2022-03-14 Bao-Fei Li , Parampreet Singh

Loop quantum cosmology in (b, v) variables, which is governed by a unit step size difference equation, is embedded into a full theory context based on similar variables. A full theory context here means a theory of quantum gravity arrived…

General Relativity and Quantum Cosmology · Physics 2016-05-20 Norbert Bodendorfer

Our review is devoted to three promising research lines in quantum cosmology and the physics of the early universe. The nonperturbative renormalization programme is making encouraging progress that we here assess from the point of view of…

General Relativity and Quantum Cosmology · Physics 2016-11-15 Giampiero Esposito

We study the generation of primordial fluctuations in pure de Sitter inflation where the quantum scalar field dynamics are governed by polymer (not Schrodinger) quantization. This quantization scheme is related to, but distinct from, the…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 Sanjeev S. Seahra , Iain A. Brown , Golam Mortuza Hossain , Viqar Husain

Loop quantum cosmology applies techniques derived for a background independent quantization of general relativity to cosmological situations and draws conclusions for the very early universe. Direct implications for the singularity problem…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Martin Bojowald

Within loop quantum gravity we construct a coarse-grained approximation for the Einstein-Maxwell theory that yields effective Maxwell equations in flat spacetime comprising Planck scale corrections. The corresponding Hamiltonian is defined…

High Energy Physics - Theory · Physics 2009-11-07 Jorge Alfaro , Hugo A. Morales-Técotl , Luis F. Urrutia

The relation between the results of cosmological N-body simulations, and the continuum theoretical models they simulate, is currently not understood in a way which allows a quantification of N dependent effects. In this first of a series of…

Astrophysics · Physics 2013-05-29 Michael Joyce , Bruno Marcos

The primordial spectrum of cosmological tensor perturbations is considered as a possible probe of quantum gravity effects. Together with string theory, loop quantum gravity is one of the most promising frameworks to study quantum effects in…

General Relativity and Quantum Cosmology · Physics 2009-04-09 J. Grain , A. Barrau

Inflationary cosmology with a preceding nonsingular bounce can lead to changes on the primordial density fluctuations. One significant prediction is that the amplitude of the power spectrum may undergo a jump at a critical scale. In this…

Cosmology and Nongalactic Astrophysics · Physics 2012-04-10 Jie Liu , Yi-Fu Cai , Hong Li

In loop quantum cosmology, non-perturbative quantum gravity effects lead to the resolution of the big bang singularity by a quantum bounce without introducing any new degrees of freedom. Though fundamentally discrete, the theory admits a…

General Relativity and Quantum Cosmology · Physics 2010-05-12 Gonzalo J. Olmo , Parampreet Singh

In this paper we consider tensor perturbations produced at a bounce phase in presence of the holonomy corrections. Here bounce phase and holonomy corrections originate from Loop Quantum Cosmology. We re-derive formulas for the corrections…

General Relativity and Quantum Cosmology · Physics 2009-07-09 Jakub Mielczarek

We study the dynamics of states perturbatively expanded about a harmonic system of loop quantum cosmology, exhibiting a bounce. In particular, the evolution equations for the first and second order moments of the system are analyzed. These…

General Relativity and Quantum Cosmology · Physics 2011-01-20 Martin Bojowald , David Mulryne , William Nelson , Reza Tavakol

Proposing smooth initial conditions is one of the most important tasks in quantum cosmology. On the other hand, the low-energy effective action, appearing in the semiclassical path integral, can get nontrivial quantum corrections near…

General Relativity and Quantum Cosmology · Physics 2018-11-07 Suddhasattwa Brahma , Dong-han Yeom

We investigate the impact of quantum fluctuations on a light rolling quintessence field from three different sources, namely, from a coupling to the standard model and dark matter, from its self-couplings and from its coupling to gravity.…

High Energy Physics - Phenomenology · Physics 2007-05-23 Mathias Garny

In this paper we investigate dynamics of the modified loop quantum cosmology models using dynamical systems methods. Modifications considered come from the choice of the different field strength operator $\hat{F}$ and result in different…

General Relativity and Quantum Cosmology · Physics 2014-11-18 Orest Hrycyna , Jakub Mielczarek , Marek Szydlowski

The power spectrum is widely used in astronomy, to analyze temporal or spatial structure. In cosmology, it is used to quantify large-scale structure (LSS) and the cosmic microwave background (CMB). This is because the power spectrum…

Cosmology and Nongalactic Astrophysics · Physics 2011-09-19 Mark C. Neyrinck

In this companion to our letter (arXiv:2208.10514), we elaborate the full details of the predicted corrections to the primordial scalar and tensor power spectra that arise from quantum gravity-motivated, natural, covariant ultraviolet…

High Energy Physics - Theory · Physics 2023-06-07 Aidan Chatwin-Davies , Achim Kempf , Petar Simidzija