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This thesis is dedicated to studying cosmological inflation, which is a period of accelerated expansion in the very early Universe that is required to explain the observed anisotropies in the cosmic microwave background. Inflation, when…

Cosmology and Nongalactic Astrophysics · Physics 2021-02-02 Chris Pattison

An approach to construct cosmological inflation models on the basis of a certain dependence of the scalar field evolution on the e-folds number is considered. The reconstruction of the model background parameters according to the kind of…

General Relativity and Quantum Cosmology · Physics 2025-12-23 Igor V. Fomin , Vladimir L. Glushkov , Evgenii S. Dentsel , Gevorg D. Manucharyan , Vyacheslav A. Sizov

The computation of the spectrum of primordial perturbations, generated by a scalar field during the super-inflationary phase of Loop Quantum Cosmology, is revisited. The calculation is performed for two different cases. The first considers…

Astrophysics · Physics 2009-11-11 D. J. Mulryne , N. J. Nunes

By incorporating quantum aspects of gravity, Loop Quantum Cosmology (LQC) provides a self-consistent extension of the inflationary scenario, allowing for modifications in the primordial inflationary power spectrum with respect to the…

Cosmology and Nongalactic Astrophysics · Physics 2019-11-01 Micol Benetti , Leila Graef , Rudnei O. Ramos

Non-perturbative quantum geometric effects in Loop Quantum Cosmology predict a $\rho^2$ modification to the Friedmann equation at high energies. The quadratic term is negative definite and can lead to generic bounces when the matter energy…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Parampreet Singh , Kevin Vandersloot , G. V. Vereshchagin

Recently, the nonperturbative quantization scheme of loop quantum gravity has been extended to the Brans-Dicke theory and the corresponding loop quantum Brans-Dicke cosmology has been derived, which provides an essential platform to explore…

General Relativity and Quantum Cosmology · Physics 2019-02-15 Wei-Jian Jin , Yongge Ma , Tao Zhu

Loop quantum cosmology allows to replace the original singularity by a quantum bounce followed by a phase of fast expansion called super-inflation. In this paper, we use a simple analytic description of super-inflation using the equation of…

General Relativity and Quantum Cosmology · Physics 2015-03-19 J. Ribassin , E. Huguet , K. Ganga

We study the effect on the primordial tensor power spectrum of varying the number of e-folds during slow-roll inflation in Loop Quantum Cosmology with a Starobinsky potential. Using the hybrid quantization approach, we derive the effective…

General Relativity and Quantum Cosmology · Physics 2025-11-20 Marceau Henry , Guillermo A. Mena Marugán , Antonio Vicente-Becerril

In this review, a pedagogical introduction to the concepts of slow-roll inflationary Universe and number of $e$-folds is provided. In particular, the differences between the basic notion of number of $e$-folds ($N_e$), total number of…

Cosmology and Nongalactic Astrophysics · Physics 2024-08-06 Alessandro Di Marco , Emanuele Orazi , Gianfranco Pradisi

We discuss a novel scenario for early cosmology, when the inflationary quasi-de Sitter phase dynamically originates from the initial quantum state represented by the microcanonical density matrix. This genuine quantum effect occurs as a…

High Energy Physics - Theory · Physics 2018-08-15 Andrey O. Barvinsky , Ariel R. Zhitnitsky

If the spatial curvature of the universe is positive, then the curvature term will always dominate at early enough times in a slow-rolling inflationary epoch. This enhances inflationary effects and hence puts limits on the possible number…

General Relativity and Quantum Cosmology · Physics 2015-06-25 G. F. R. Ellis , W. Stoeger , P. McEwan , P. Dunsby

We consider the effects on the primordial power spectrum of a period of radiation-dominated expansion prior to the inflationary era. If inflation lasts a total of only 60 e-folds or so, the boundary condition for quantum modes cannot be…

Astrophysics · Physics 2008-11-26 Brian A. Powell , William H. Kinney

We study the pattern of oscillations in the primordial power spectrum in axion monodromy inflation, accounting for drifts in the oscillation period that can be important for comparing to cosmological data. In these models the potential…

High Energy Physics - Theory · Physics 2017-11-15 Raphael Flauger , Liam McAllister , Eva Silverstein , Alexander Westphal

Inflation in cosmology is a specific stage preceding the Big Bang, aimed at solving both old background problems and new perturbation issues. Single-field inflation is a candidate to illustrate the picture of the initial universe, and…

Cosmology and Nongalactic Astrophysics · Physics 2025-05-21 Guanqiao Liu

We examine the quantum loop effects on the single-field inflationary models in a spatially flat Friedmann-Robertson-Walker (FRW) cosmological space-time with a general self-interacting scalar field potential, which is modeled in terms of…

General Relativity and Quantum Cosmology · Physics 2020-02-05 Wei-Can Syu , Da-Shin Lee , Kin-Wang Ng

We explore a reduced phase space quantization of loop quantum cosmology (LQC) for a spatially flat FLRW universe filled with reference fields and an inflaton field in a Starobinsky inflationary potential. We consider three separate cases in…

General Relativity and Quantum Cosmology · Physics 2021-01-04 Kristina Giesel , Bao-Fei Li , Parampreet Singh

The usual description of inflationary fluctuations uses the framework of quantum field theory (QFT) in curved spacetime, in which quantum fluctuations are superimposed on a classical background spacetime. Even for large fluctuations, such…

General Relativity and Quantum Cosmology · Physics 2020-03-11 Sebastian F. Bramberger , Alice Di Tucci , Jean-Luc Lehners

In this paper, we systematically study the evolution of the Universe in the framework of a modified loop quantum cosmological model (mLQC-I) with various inflationary potentials, including chaotic, Starobinsky, generalized Starobinsky,…

General Relativity and Quantum Cosmology · Physics 2024-10-22 Jamal Saeed , Rui Pan , Christian Brown , Gerald Clevear , Anzhong Wang

We investigate how various inflationary and bouncing cosmologies can be realized by imperfect fluids with a generalized equation of state, in the context of both classical and loop quantum cosmology. With regards to the inflationary…

General Relativity and Quantum Cosmology · Physics 2017-09-06 V. K. Oikonomou

We present new single field inflationary scenarios that produce the critical abundance of primordial black holes as dark matter reconstructing the inflaton potential from an input power spectrum. The method is exact in the slow roll…

Cosmology and Nongalactic Astrophysics · Physics 2024-12-11 Gabriele Autieri , Michele Redi