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We study how the initial inhomogeneities of the universe affect the onset of inflation in the closed universe. We consider the model of a chaotic inflation which is driven by a massive scalar field. In order to construct an inhomogeneous…

General Relativity and Quantum Cosmology · Physics 2009-10-28 Osamu Iguchi , Hideki Ishihara

The possibility of having an inflationary epoch within a noncommutative geometry approach to unifying gravity and the standard model is demonstrated. This inflationary phase occurs without the need to introduce "ad hoc" additional fields or…

High Energy Physics - Theory · Physics 2010-01-26 William Nelson , Mairi Sakellariadou

We consider a model of inflation which has recently been proposed in the literature and where inflation is induced by corrections to the energy density coming from the non-commutativity of spacetime. We show that the very rapid inflationary…

General Relativity and Quantum Cosmology · Physics 2013-01-14 Hideki Perrier , Ruth Durrer , Massimiliano Rinaldi

In the standard cosmological picture the Universe underwent a brief period of near-exponential expansion, known as Inflation. This provides an explanation for structure formation through the amplification of perturbations by the rapid…

General Relativity and Quantum Cosmology · Physics 2019-04-03 Zack Fifer , Theo Torres , Sebastian Erne , Anastasios Avgoustidis , Richard J. A. Hill , Silke Weinfurtner

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

Inflation may have been driven by a component which violated the Null-Energy Condition, thereby leading to {\it super inflation}. We provide the formalism to study cosmological perturbations when such a component is described by a scalar…

Astrophysics · Physics 2010-09-21 Marco Baldi , Fabio Finelli , Sabino Matarrese

We consider spatially averaged inhomogeneous universe models and argue that, already in the absence of sources, an effective scalar field arises through foliating and spatially averaging inhomogeneous geometrical curvature invariants of the…

General Relativity and Quantum Cosmology · Physics 2011-07-26 Thomas Buchert , Nathaniel Obadia

We consider the scale-invariant inflationary model studied in [1]. The Lagrangian includes all the scale-invariant operators that can be built with combinations of $R$, $R^2$ and one scalar field. The equations of motion show that the…

General Relativity and Quantum Cosmology · Physics 2017-03-14 Giovanni Tambalo , Massimiliano Rinaldi

We suggest a new conceptual frame where inflationary Cosmology is quantum mechanically described using the Hilbert space representation of the crossed product of the type $III$ factor associated with the algebra of local operators on the de…

High Energy Physics - Theory · Physics 2022-07-15 Cesar Gomez

Potentials in cosmological inflation often involve scalars with trans-Planckian ranges. As a result, towers of states become massless and their presence pushes the fundamental scale not to coincide with $M_{\rm P}$ but rather with the…

High Energy Physics - Theory · Physics 2024-09-17 Gonzalo F. Casas , Luis E. Ibáñez

Modak and Singleton [Phys. Rev. D 86, 123515 (2012)] have presented Hawking-like radiation for cosmological inflation which has a natural "turn on" and a natural "turn off" mechanism. This Hawking-like radiation results in an effective…

General Relativity and Quantum Cosmology · Physics 2015-06-17 Javad T. Firouzjaee

I study a model which describes the birth of the universe using a global topological phase transition with a complex manifold where the time, $\tau$, is considered as a complex variable. Before the big bang $\tau$ is a purely imaginary…

General Relativity and Quantum Cosmology · Physics 2017-05-24 Mauricio Bellini

We investigate the entropy dynamics of de Sitter spacetime during the inflationary phase. The cosmological horizon in de Sitter spacetime, which limits the causally accessible region for an observer, exhibits thermal properties similar to a…

High Energy Physics - Theory · Physics 2025-03-24 Hiromasa Tajima , Yasusada Nambu

Loop quantum cosmology with a scalar field is known to be closely linked with an inflationary phase. In this article, we study probabilistic predictions for the duration of slow-roll inflation, by assuming a minimalist massive scalar field…

General Relativity and Quantum Cosmology · Physics 2014-07-28 Linda Linsefors , Aurelien Barrau

We consider the eternal inflation scenario of the slow-roll/chaotic type with the additional element of an objective collapse of the wave function. The incorporation of this new agent to the traditional inflationary setting might represent…

General Relativity and Quantum Cosmology · Physics 2017-10-27 Gabriel Leon

A continuous process of creation of particles is investigated as a possible connection between the inflationary stage with late cosmic acceleration. In this model, the inflationary era occurs due to a continuous and fast process of creation…

General Relativity and Quantum Cosmology · Physics 2016-04-27 Rafael C. Nunes

Starobinsky has suggested an inflation model which is obtained from the vacuum Einstein's equations modified by the one-loop corrections due to quantized matter fields. Although the one-loop gravitational action is not known for a general…

Cosmology and Nongalactic Astrophysics · Physics 2018-04-06 Seokcheon Lee

If the cosmological inflationary scenario took place in the cosmic landscape in string theory, the inflaton, the scalar mode responsible for inflation, would have meandered in a complicated multi-dimensional potential. We show that this…

High Energy Physics - Theory · Physics 2010-01-21 S. -H. Henry Tye , Jiajun Xu

Quantum geometry predicts that a universe evolves through an inflationary phase at small volume before exiting gracefully into a standard Friedmann phase. This does not require the introduction of additional matter fields with ad hoc…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Martin Bojowald

In this paper, we consider a nonminimal coupling model between gravity and nonlinear electrodynamics with cosmological constant. This cosmological model is designed to account for both the inflationary epoch of the early universe and the…

General Relativity and Quantum Cosmology · Physics 2024-10-10 Chilwatun Nasiroh , Ramy F. Izzah , Fiki T. Akbar , Bobby E. Gunara