The<i>N</i>-vaton

Huang, Qing-Guo

doi:10.1088/1475-7516/2008/09/017

Cited by 44 publications

(43 citation statements)

References 81 publications

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“…The evolutions of power spectra with respect to e-folding number N Ã À N after crossing the horizon. This figure is drawn according to the model with action (48). From top to bottom: curvature power spectrum P R , entropy power spectrum P S (dashed blue line) and cross-correlation power spectrum P C (dot-dashed purple line), tensor power spectrum P T .…”

Section: =R Correction To Inflationmentioning

confidence: 99%

“…The vertical dotted black lines correspond to N Ã À N ¼ 60. , entropy-to-curvature ratio r S (its logarithm, middle graph), and tensor-to-scalar ratio r T (lower graph) with respect to e-folding number N Ã À N after crossing the horizon. This figure is drawn according to the model with action (48). The vertical dotted black lines correspond to N Ã À N ¼ 60.…”

Section: =R Correction To Inflationmentioning

confidence: 99%

“…On the other hand, the smallness of the cosmological constant requires 2 =M 2 p $ 10 À121 in action (2). In other words, if one intends to use model (48) to explain the comic microwave background (CMB) anisotropy, the residual ''dark energy'' will be too large compared with the observed value. For this reason, we conclude the model (48) with a quadratic potential is unattractive.…”

Section: =R Correction To Inflationmentioning

confidence: 99%

“…The vertical dotted black line corresponds to N Ã À N ¼ 60. This figure is drawn according to the model with action(48).…”

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confidence: 99%

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1/Rcorrection to gravity in the early universe

Wang

2009

Phys. Rev. D

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To explain the accelerated expansion of the late universe, the 1=R correction to Einstein gravity is usually considered, where R is the Ricci scalar. This correction term, if stable, is generally believed to be negligible during inflation. However, if the 1=R term is inflaton dependent, it will dramatically change the story of inflation. The entropy perturbation will naturally appear and drive the evolution of curvature perturbation outside the Hubble horizon. In a large class of models, the entropy perturbation can be made nearly scale invariant. In Einstein gravity the single-field inflation with a quartic potential has been ruled out by recent observations, but it revives when the 1=R term is turned on. The evolution of nonGaussianities on a large scale are also studied and applied to inflation with 1=R correction. In some specific models, a large non-Gaussianity can be naturally generated outside the horizon. A recent study ruled out almost all fðRÞ models during the matter-dominated phase. Taking this into consideration, we are left with a limited class of model which recovers the Einstein gravity soon after reheating.

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Section: =R Correction To Inflationmentioning

confidence: 99%

Section: =R Correction To Inflationmentioning

confidence: 99%

Section: =R Correction To Inflationmentioning

confidence: 99%

“…The vertical dotted black line corresponds to N Ã À N ¼ 60. This figure is drawn according to the model with action(48).…”

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confidence: 99%

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1/Rcorrection to gravity in the early universe

Wang

2009

Phys. Rev. D

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“…Beyond the simplest model of the curvaton, there are various possibilities; the inflaton perturbation may not be negligible [32], the curvaton can have different types of potential [33][34][35][36] and there could be multiple curvaton fields [37][38][39]. Significant effects on non-Gaussianity due to non-quadratic terms can be seen [40][41][42][43][44][45].…”

Section: Introductionmentioning

confidence: 99%

Non-Gaussianity and gravitational wave background in curvaton with a double well potential

Choi

Seto

2010

Phys. Rev. D

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We study the density perturbation by a curvaton with a double well potential and estimate the nonlinear parameters for non-Gaussianity and the amplitude of gravitational wave background generated during inflation. The predicted nonlinear parameters strongly depend on the size of a curvaton self-coupling constant as well as the reheating temperature after inflation for a given initial amplitude of the curvaton. The difference from usual massive self-interacting curvaton is also emphasized. PACS numbers: 95.85.Bh, 98.80.Es, 98.80.Cq

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Reconstruction of f(T) gravity from the Holographic Dark Energy

Chattopadhyay¹,

Pasqua

2012

Astrophys Space Sci

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Among different candidates to play the role of Dark Energy (DE), modified gravity has emerged as offering a possible unification of Dark Matter (DM) and DE. The purpose of this work is to develop a reconstruction scheme for the modified gravity with f (T ) action using holographic energy density. In the framework of the said modified gravity we have considered the equation of state of the Holographic DE (HDE) density. Subsequently we have developed a reconstruction scheme for modified gravity with f (T ) action. Finally we have obtained a modified gravity action consistent with the HDE scenario. PACS numbers: 98.80.-k, 95.36.+x, 04.50.Kd I. INTRODUCTION Cosmological observations obtained with Supernovae Ia (SNeIa), the Cosmic Microwave Background (CMB) radiation anisotropies, the Large Scale Structure (LSS) and X-ray experiments have well established the accelerated expansion of our universe [1-7]. A missing energy component also known as Dark Energy (DE) with negative pressure is widely considered by scientists as responsible of this accelerated expansion. Recent analysis of cosmological observations indicates that the two-thirds of the total energy of the universe is been occupied by the DE whereas DM occupies almost the remaining part (the baryonic matter represents only a few percent of the total energy density of the universe) [8]. The contribution of the radiation is practically negligible.The nature of DE is still unknown and many candidates have been proposed in order to describe it [9][10][11][12][13][14][15][16]. The simplest one is represented by a tiny positive cosmological constant, with a negative constant equation of state (EoS) parameter ω, i.e. ω = −1. However, cosmologists know that the cosmological constant suffers from two well-known difficulties, the fine-tuning and the cosmic coincidence problems: the former asks why the vacuum energy density is so small (of the order of * Electronic address: surajit˙2008@yahoo.co.in, surajcha@iucaa.ernet.in † Electronic address: toto.pasqua@gmail.com

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TheN-vaton

Cited by 44 publications

References 81 publications

1/Rcorrection to gravity in the early universe

1/Rcorrection to gravity in the early universe

Non-Gaussianity and gravitational wave background in curvaton with a double well potential

Reconstruction of f(T) gravity from the Holographic Dark Energy

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