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200 papers

The unifying approach to early-time and late-time universe based on phantom cosmology is proposed. We consider gravity-scalar system which contains usual potential and scalar coupling function in front of kinetic term. As a result, the…

High Energy Physics - Theory · Physics 2009-09-17 Shin'ichi Nojiri , Sergei D. Odintsov

We develop the relation between de Sitter holography and inflation in detail, with particular attention to cosmic density perturbations. We set up the Hamilton-Jacobi formalism to present a systematic treatment of the logarithmic…

High Energy Physics - Theory · Physics 2010-02-03 Finn Larsen , Robert McNees

The holographic entropy bound is used to estimate the quantum-gravitational discreteness of inflationary perturbations. In the context of scalar inflaton perturbations produced during standard slow-roll inflation, but assuming that…

Astrophysics · Physics 2009-11-07 Craig J. Hogan

Anisotropic inflation is a model succeeded in explaining statistical anisotropy. Warm inflation is a model succeeded in providing a mechanism of reheating during inflation. We study anisotropic warm inflation focusing on the cosmic no-hair…

High Energy Physics - Theory · Physics 2023-06-09 Sugumi Kanno , Ann Mukuno , Jiro Soda , Kazushige Ueda

Holographic duality provides a description of strongly coupled quantum systems in terms of weakly coupled gravitational theories in a higher-dimensional space. It is a challenge, however, to quantitatively determine the physical parameters…

High Energy Physics - Theory · Physics 2021-09-08 Paul Wittmer , Christian-Marcel Schmied , Thomas Gasenzer , Carlo Ewerz

We study a scenario for the very early universe in which there is a fast phase transition from a non-geometric, high temperature phase to a low temperature, geometric phase described by a classical solution to the Einstein equations. In…

Astrophysics · Physics 2008-11-26 Joao Magueijo , Lee Smolin , Carlo R. Contaldi

We study a warm inflationary model for different expansions assuming an anisotropic universe described by Bianchi I metric. The universe is filled with a scalar field or inflaton, radiation, and bulk viscous pressure. We carry out the…

General Relativity and Quantum Cosmology · Physics 2022-02-07 Mehdi Shokri , Jafar Sadeghi , Ramón Herrera , Saeed Noori Gashti

The Higgs field is an attractive candidate for the inflaton because it is an observationally confirmed fundamental scalar field. Importantly, it can be modeled by the most general renormalizable scalar potential. However, if the classical…

Cosmology and Nongalactic Astrophysics · Physics 2021-03-29 Martin Bojowald , Suddhasattwa Brahma , Sean Crowe , Ding Ding , Joseph McCracken

Cosmological inflation provides the simplest and most promising mechanism for generating fluctuations for structure formation. Using powerful Hamilton-Jacobi methods, I will describe (1) how to compute density fluctuations and cosmic…

Astrophysics · Physics 2009-09-25 D. S. Salopek

The encoding of an inflating patch of space-time in terms of a dual theory is discussed. Following Bousso's interpretation of the holographic principle, we find that those are generically described not by states in the dual theory but by…

High Energy Physics - Theory · Physics 2009-11-07 Bruno Carneiro da Cunha

Holography is expected as one of the promising descriptions of quantum general relativity. We present a model for a cosmological system involving two holographic screens and find that their equilibrium exactly yields a standard…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 Yi-Fu Cai , Jie Liu , Hong Li

It has become standard practice to take the logarithmic growth of the scale factor as a measure of the amount of inflation, despite the well-known fact that this is only an approximation for the true amount of inflation required to solve…

Cosmology and Nongalactic Astrophysics · Physics 2016-09-02 Sirichai Chongchitnan

We briefly review several Higgs inflation models and discuss their cosmological implications. We first classify the inflation models according to the predicted value of the tensor-to-scalar ratio: (i) $r = {\cal O}(0.01-0.1)$, (ii) $r =…

High Energy Physics - Phenomenology · Physics 2015-06-01 Fuminobu Takahashi

We describe a cosmology of the very early universe, based on the holographic principle of 't Hooft and Susskind. We have described the initial state as a dense black hole fluid. Here we present a mathematical model of this heuristic…

High Energy Physics - Theory · Physics 2016-02-09 T. Banks , W. Fischler

Inflationary models usually assume the existence of scalar fields or other exotic gravitational sources. We investigate an alternative approach in which the entire Universe is considered as a thermodynamic system described by…

General Relativity and Quantum Cosmology · Physics 2018-04-10 Christine Gruber , Hernando Quevedo

Following recent studies of Ford, we suggest -- in the framework of general relativity -- an inflationary cosmological model with the self-interacting spinning matter. A generalization of the standard fluid model is discussed and estimates…

General Relativity and Quantum Cosmology · Physics 2010-11-01 Yuri N. Obukhov

Using the holographic entropy proposal for a closed universe by Verlinde, a bound on equations of state for different stages of the universe is obtained. Further exploring this bound, we find that an inflationary universe naturally emerges…

High Energy Physics - Theory · Physics 2007-05-23 Qing-Guo Huang

In this paper, we build upon the successes of the ultraviolet (UV) completion of the Starobinsky model of inflation. This involves an extension of the Einstein-Hilbert term by an infinite covariant derivative theory of gravity, which is…

General Relativity and Quantum Cosmology · Physics 2017-11-15 James Edholm

Recently Eling and Oz (EO) proposed a formula for the holographic bulk viscosity, in arXiv:1103.1657, derived from the null horizon focusing equation. This formula seems different from that obtained earlier by Gubser, Pufu and Rocha (GPR)…

High Energy Physics - Theory · Physics 2015-03-19 Alex Buchel , Umut Gursoy , Elias Kiritsis

Inflation can be parameterized by means of truncated flow equations. In this "horizon-flow" setup, generic results have been obtained, such as typical values for $r/(1-n_\mathrm{S})$. They are sometimes referred to as intrinsic features of…

Cosmology and Nongalactic Astrophysics · Physics 2014-10-08 Vincent Vennin