Scalar–tensor models of normal and phantom dark energy

Gannouji, Radouane; Polarski, David; André, Ranquet; Starobinsky, Alexei A.

doi:10.1088/1475-7516/2006/09/016

Cited by 223 publications

(204 citation statements)

References 78 publications

(201 reference statements)

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“…Since we are interested in the observational consequences of equations (2.7)-(2.10) at low redshifts, we consider expansions of equations (2.5) and (2.6) around z = 0 expanding F (z), H(z) 2 U (z), Φ(z) as follows [29]:…”

Section: The Boundaries Of Extended Quintessencementioning

confidence: 99%

Limits of extended quintessence

2007

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We use a low redshift expansion of the cosmological equations of extended (scalar-tensor) quintessence to divide the observable Hubble history parameter space in four sectors: A forbidden sector I where the scalar field of the theory becomes imaginary (the kinetic term becomes negative), a forbidden sector II where the scalar field rolls up (instead of down) its potential, an allowed 'freezing' quintessence sector III where the scalar field is currently decelerating down its potential towards freezing and an allowed 'thawing' sector IV where the scalar field is currently accelerating down its potential. The dividing lines between the sectors depend sensitively on the time derivatives of the Newton's constant G over powers of the Hubble parameter. For minimally coupled quintessence which appears as a special case for a constant G our results are consistent with previous studies. Observable parameter χ 2 contours based on current data (SNLS dataset) are also constructed on top of the sectors, for a prior of Ωm = 0.24. By demanding that the observed 2σ χ 2 parameter contours do not lie entirely in the forbidden sectors we derive stringent constraints on the current second time derivative of Newton's constant G. In particular we find G G > −1.91 H 2 0 = −2 × 10 −20 h 2 yrs −2 at the 2σ level which is complementary to solar system tests which constrain only the first derivative of G as |Ġ G | < 10 −14 yrs −1 at 1σ.

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Section: The Boundaries Of Extended Quintessencementioning

confidence: 99%

Limits of extended quintessence

2007

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“…Perhaps the most studied and the simplest one of these couplings is the non-minimal coupling of the type ξRφ 2 . The role of this coupling in the dark energy (DE) problem has been studied in different works, including the constraint on ξ by solar system experiments [12], the existence and stability of cosmological scaling solutions [13,14], perturbative aspects and incidence on CMB [34,35], tracker solutions [36], observational constraints and reconstruction [37][38][39], the coincidence problem [40], super acceleration and phantom behavior [41]- [45], and asymptotic de Sitter attractors [46]. Another interesting interaction that gives good results in the study of the dark energy is the coupling between the scalar field and the Gauss-Bonnet (GB) invariant .…”

Section: Introductionmentioning

confidence: 99%

Dark energy from Gauss-Bonnet and nonminimal couplings

Granda

Jimenez

2014

Phys. Rev. D

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We consider a scalar-tensor model of dark energy with Gauss-Bonnet and non-minimal couplings. Exact cosmological solutions were found in absence of potential, that give equations of state of dark energy consistent with current observational constraints, but with different asymptotic behaviors depending on the couplings of the model. A detailed reconstruction procedure is given for the scalar potential and the Gauss-Bonnet coupling for any given cosmological scenario. Particularly, we consider conditions for the existence of a variety of cosmological solutions with accelerated expansion, including quintessence, phantom, de Sitter, Little Rip. For the case of quintessence and phantom we have found a scalar potential of the Albrecht-Skordis type, where the potential is an exponential with a polynomial factor. PACS numbers: 98.80. 95.36.+x, 04.50.Kd

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“…We obtain from equation (46) Figure 11 shows the variation of ρ ef f DE versus ξ in a constant time slice. The range of ξ are chosen from [67][68][69][70][71] constraint by the recent observations. As this figure shows, by increasing the values of the nonminimal coupling, ρ ef f DE decreases in a fixed redshift( fixed time slice).…”

Section: Lue-starkman Screening Of the Brane Cosmological Constantmentioning

confidence: 99%

Phantom Mimicry on the Normal Branch of a DGP-Inspired Braneworld Scenario With Curvature Effect

Nozari

Alipour

2010

Mod. Phys. Lett. A

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It has been shown recently that phantom-like effect can be realized on the normal branch of the DGP setup without introduction of any phantom matter neither in the bulk nor on the brane and therefore without violation of the null energy condition. It has been shown also that inclusion of the Gauss-Bonnet term in the bulk action modifies this picture via curvature effects. Here, based on the Lue-Starkman conjecture on the dynamical screening of the brane cosmological constant in the DGP setup, we extend this proposal to a general DGP-inspired f (R, φ) model that stringy effects in the ultraviolet sector of the theory are taken into account by inclusion of the Gauss-Bonnet term in the bulk action. We study cosmological dynamics of this setup, especially its phantom-like behavior and possible crossing of the phantom divide line especially with a non-minimally coupled quintessence field on the brane. In this setup, scalar field and curvature quintessence are treated in a unified framework. 95.36.+x, 98.80.Cq

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Scalar–tensor models of normal and phantom dark energy

Cited by 223 publications

References 78 publications

Limits of extended quintessence

Limits of extended quintessence

Dark energy from Gauss-Bonnet and nonminimal couplings

Phantom Mimicry on the Normal Branch of a DGP-Inspired Braneworld Scenario With Curvature Effect

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