Cosmological consequences of a rolling homogeneous scalar field

Ratra, Bharat; Peebles, P. J. E.

doi:10.1103/physrevd.37.3406

Cited by 4,198 publications

(4,193 citation statements)

References 73 publications

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“…Beyond a bare cosmological constant, a plethora of other models have been proposed, with quintessence -a dynamical scalar field that behaves essentially as a modern day inflaton field, -being perhaps the simplest example (see [11][12][13][14]). …”

Section: Introductionmentioning

confidence: 99%

Ghosts, instabilities, and superluminal propagation in modified gravity models

Felice

Hindmarsh

Trodden

2006

J. Cosmol. Astropart. Phys.

165

167

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We consider Modified Gravity models involving inverse powers of fourth-order curvature invariants.Using these models' equivalence to the theory of a scalar field coupled to a linear combination of the invariants, we investigate the properties of the propagating modes. Even in the case for which the fourth derivative terms in the field equations vanish, we find that the second derivative terms can give rise to ghosts, instabilities, and superluminal propagation speeds. We establish the conditions which the theories must satisfy in order to avoid these problems in Friedmann backgrounds, and show that the late-time attractor solutions generically exhibit superluminally propagating tensor or scalar modes. * a. de-felice@sussex.ac.uk

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Section: Introductionmentioning

confidence: 99%

Ghosts, instabilities, and superluminal propagation in modified gravity models

Felice

Hindmarsh

Trodden

2006

J. Cosmol. Astropart. Phys.

165

167

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“…We assume that f (φ) = f 0 φ κ and V (φ) = V 0 φ δ where κ and δ are dimensionless constants characterizing the slope of potential V (φ) and f (φ). The cosmological models with such exponential functions have been known lead to interesting physics in a variety of context, ranging from existence of accelerated expansions [35] to cosmological scaling solutions [36]- [37]. In particular, the exponential forms of f (φ) and V (φ) are motivated by chameleon models [32] and also from stability considerations [38].…”

Section: The Modelmentioning

confidence: 99%

Stability analysis and observational measurement in chameleonic generalised Brans-Dicke cosmology

Farajollahi

Salehi

2011

J. Cosmol. Astropart. Phys.

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We investigate the dynamics of the chameleonic Generalised Brans-Dicke model in flat FRW cosmology. In a new approach, a framework to study stability and attractor solutions in the phase space is developed for the model by simultaneously best fitting the stability and model parameters with the observational data. The results show that for an accelerating universe the phantom crossing does not occur in the past and near future.

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“…One of the simplest models for quintessence is a scalar field rolling down an exponential potential [3]. Exponential potentials are natural in theories with extra compact dimensions, such as Kaluza-Klein supergravity and superstring models [4].…”

Section: Introductionmentioning

confidence: 99%

Fine Tuning in Quintessence Models with Exponential Potentials

França¹,

Rosenfeld²

2002

J. High Energy Phys.

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We explore regions of parameter space in a simple exponential model of the form V = V 0 e −λ(Q/Mp) that are allowed by observational constraints. We find that the level of fine tuning in these models is not different from more sophisticated models of dark energy. We study a transient regime where the parameter λ has to be less than √ 3 and the fixed point Ω Q = 1 has not been reached. All values of the parameter λ that lead to this transient regime are permitted. We also point out that this model can accelerate the universe today even for λ > √ 2, leading to a halt of the present acceleration of the universe in the future thus avoiding the horizon problem. We conclude that this model can not be discarded by current observations.

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Cosmological consequences of a rolling homogeneous scalar field

Cited by 4,198 publications

References 73 publications

Ghosts, instabilities, and superluminal propagation in modified gravity models

Ghosts, instabilities, and superluminal propagation in modified gravity models

Stability analysis and observational measurement in chameleonic generalised Brans-Dicke cosmology

Fine Tuning in Quintessence Models with Exponential Potentials

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