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An important unsolved problem that affects practically all attempts to connect string theory to cosmology and phenomenology is how to distinguish effective field theories belonging to the string landscape from those that are not consistent…

High Energy Physics - Theory · Physics 2019-02-20 Ana Achúcarro , Gonzalo A. Palma

The Wheeler--DeWitt equation for a flat and compact Friedmann--Lema\^{i}tre--Robertson--Walker cosmology at the pre-inflation epoch is studied in the contexts of the standard and fractional quantum cosmology. Working within the…

General Relativity and Quantum Cosmology · Physics 2023-04-17 S. M. M. Rasouli , E. W. Oliveira Costa , P. V. Moniz , S. Jalalzadeh

We investigate the early-time accelerated universe after the Big Bang. We pay attention to the dissipative properties of the inflationary universe in the presence of a soft type singularity, making use of the parameters of the generalized…

General Relativity and Quantum Cosmology · Physics 2017-03-23 I. Brevik , A. V. Timoshkin

We show that in generic supergravity theories the mass of the moduli during inflation is larger (or at least of the same order of magnitude) than the Hubble constant. This fact does not depends on the details of the inflation and on the…

High Energy Physics - Phenomenology · Physics 2015-07-29 Gia Dvali

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

A sum rule has been derived for the static pair correlation function. This rule is the extension of the well-known equation that relates density fluctuation to compressibility. The obtained sum rule is applied to the Bose and Fermi ideal…

Statistical Mechanics · Physics 2007-05-23 A. Yu. Cherny

In most current models of inflation based on a weakly self-coupled scalar matter field minimally coupled to gravity, the period of inflation lasts so long that, at the beginning of the inflationary period, the physical wavelengths of…

High Energy Physics - Theory · Physics 2008-11-26 Jerome Martin , Robert H. Brandenberger

We quantify the slow-roll corrections to primordial density perturbations arising from inflation driven by a four-dimensional scalar field with a monomial potential in a five-dimensional non-compact bulk spacetime. Although the difference…

Astrophysics · Physics 2008-11-26 Kazuya Koyama , Andrew Mennim , David Wands

Inflationary cosmology is the leading explanation of the very early universe. Many different models of inflation have been constructed which fit current observational data. In this work theoretical and numerical methods for constraining the…

Cosmology and Nongalactic Astrophysics · Physics 2010-06-29 Ian Huston

We discuss how holographic bounds can be applied to the quantum fluctuations of the inflaton. In general the holographic principle will lead to a bound on the UV cutoff scale of the effective theory of inflation, but it will depend on the…

High Energy Physics - Theory · Physics 2009-11-10 Esko Keski-Vakkuri , Martin S. Sloth

The purpose of these lectures is to give a pedagogical introduction to inflation and the production of primordial perturbations, as well as a review of some of the latest developments in this domain. After a short introduction, we review…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 David Langlois

In loop quantum gravity, modifications to the geometrical density cause a self-interacting scalar field to accelerate away from a minimum of its potential. In principle, this mechanism can generate the conditions that subsequently lead to…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Martin Bojowald , James E. Lidsey , David J. Mulryne , Parampreet Singh , Reza Tavakol

Power spectra play an important role in the theory of inflation, and their ability to reproduce current observational data to high accuracy is often considered a triumph of inflation, largely because of a lack of credible alternatives. In…

Cosmology and Nongalactic Astrophysics · Physics 2020-05-21 Herbert W. Hamber , Lu Heng Sunny Yu , Hasitha E. Pituwala Kankanamge

We present a mechanism for the emergence of cosmic acceleration within the mean-field approximation of Group Field Theory models of quantum gravity. Depending on the interaction type, the resulting cosmological dynamics can either feature a…

General Relativity and Quantum Cosmology · Physics 2025-12-15 Luca Marchetti , Tom R. Ladstätter , Daniele Oriti

The inflationary and pre-inflationary evolution of scalar modes of cosmological perturbations in a closed universe is analyzed for a loop quantum cosmology model with an inflationary regime consistent with the constraints on inflation…

General Relativity and Quantum Cosmology · Physics 2024-11-26 Lucas M. V. Montese , Nelson Yokomizo

The hypothesis that the Universe underwent a period of exponential expansion at very early times has become the most popular theory of the early Universe. Not only does it solve some of the problems of standard big bang cosmology, but it…

Astrophysics · Physics 2007-05-23 Robert H. Brandenberger

The inflationary cosmology is analyzed from the point of view of squeezed quantum states. As noted by Grishchuk and Sidorov, the amplification of quantum fluctuations into macroscopic perturbations which occurs during cosmic inflation is a…

Astrophysics · Physics 2010-04-08 Andreas Albrecht , Pedro Ferreira , Michael Joyce , Tomislav Prokopec

Penrose [1] has emphasized how the initial big bang singularity requires a special low entropy state. We address how recent brane cosmological schemes address this problem and whether they offer any apparent resolution. Pushing the start…

General Relativity and Quantum Cosmology · Physics 2016-08-31 D. H. Coule

We develop a cosmological model where primordial inflation is driven by a 'solid', defined as a system of three derivatively coupled scalar fields obeying certain symmetries and spontaneously breaking a certain subgroup of these. The…

High Energy Physics - Theory · Physics 2015-06-11 Solomon Endlich , Alberto Nicolis , Junpu Wang

We reconsider a string theoretic inflationary model, where inflation is driven by $n$ multiple coincident $D3$-branes in the finite $n$ limit. We show that the finite $n$ action can be continued to the limit of large $n$, where it converges…

High Energy Physics - Theory · Physics 2010-01-22 Aaron Berndsen , James. E. Lidsey , John Ward
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