Brans-Dicke cosmology does not have the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi mathvariant="normal">Λ</mml:mi><mml:mi>CDM</mml:mi></mml:mrow></mml:math>phase as a universal attractor

García-Salcedo, Ricardo; González, Tamé; Quirós, Israel

doi:10.1103/physrevd.92.124056

Cited by 19 publications

(18 citation statements)

References 83 publications

(234 reference statements)

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“…J 4 represents an accelerating solution with w tot = −1. At the end of section 2.3 we will discuss on the corresponding asymptotics giving new arguments supporting the statements in [26] against [19][20][21]. Indeed, J 4 represents an intermediate solution at late time, i.e., a(t) ≃ e α 1 t p 1 as t → ∞ where α 1 > 0, and…”

Section: J 3 Is a Scaling Solution Between ω Effmentioning

confidence: 88%

“…Summarizing, we have explicitly shown that the solutions near J 4 satisfy Φ ∼ 1 t p 1 , ΦR ≃ At p 1 −2 + Bt −2 and H ≃ α 1 p 1 t p 1 −1 , which tend asymptotically to zero but never reach this value. Besides, the effective gravitational coupling (the one measured in Cavendish-like experiments) [26],…”

Section: Viability Of the Intermediate Accelerated Solution In The Jomentioning

confidence: 99%

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Intermediate accelerated solutions as generic late-time attractors in a modified Jordan-Brans-Dicke theory

Cid

León

Leyva

2016

J. Cosmol. Astropart. Phys.

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In this paper we investigate the evolution of a Jordan-Brans-Dicke scalar field, Φ, with a power-law potential in the presence of a second scalar field, φ, with an exponential potential, in both the Jordan and the Einstein frames. We present the relation of our model with the induced gravity model with power-law potential and the integrability of this kind of models is discussed when the quintessence field φ is massless, and has a small velocity. The fact that for some fine-tuned values of the parameters we may get some integrable cosmological models, makes our choice of potentials very interesting. We prove that in Jordan-Brans-Dicke theory, the de Sitter solution is not a natural attractor. Instead, we show that the attractor in the Jordan frame corresponds to an "intermediate accelerated" solution of the form a(t) ≃ e α 1 t p 1 , as t → ∞ where α 1 > 0 and 0 < p 1 < 1, for a wide range of parameters. Furthermore, when we work in the Einstein frame we get that the attractor is also an "intermediate accelerated" solution of the form a(t) ≃ e α 2 t p 2 as t → ∞ where α 2 > 0 and 0 < p 2 < 1, for the same conditions on the parameter space as in the Jordan frame. In the special case of a quadratic potential in the Jordan frame, or for a constant potential in the Einstein's frame, the above intermediate solutions are of saddle type. These results were proved using the center manifold theorem, which is not based on linear approximation. Finally, we present a specific elaboration of our extension of the induced gravity model in the Jordan frame, which corresponds to a particular choice of a linear potential of Φ. The dynamical system is then reduced to a two dimensional one, and the late-time attractor is linked with the exact solution found for the induced gravity model. In this example the "intermediate accelerated" solution does not exist, and the attractor solution has an asymptotic de Sitter-like evolution law for the scale factor. Apart from some fine-tuned examples such as the linear, and quadratic potential U (Φ) in the Jordan frame, it is true that "intermediate accelerated" solutions are generic late-time attractors in a modified Jordan-Brans-Dicke theory.

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Section: J 3 Is a Scaling Solution Between ω Effmentioning

confidence: 88%

Section: Viability Of the Intermediate Accelerated Solution In The Jomentioning

confidence: 99%

Intermediate accelerated solutions as generic late-time attractors in a modified Jordan-Brans-Dicke theory

Cid

León

Leyva

2016

J. Cosmol. Astropart. Phys.

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“…Studies of scalar-tensor theories have been performed by one of the present authors using these techniques [14,16], and similar and complementary analysis can be found in the literature that followed [18,19,30,31,33,34]. Some of these works focus their analysis to the case of Brans-Dicke theory [30,33,34], while others investigations consider more general scalar-tensor theories.…”

Section: Scalar-tensor Gravity Theoriesmentioning

confidence: 75%

“…The qualitative behaviour depicted in Figure 3 reveals that with the exception of the oscillatory solutions, confined to a closed patch, all other solutions emerge from a collapsing deS solution at X = ∞, X = −∞ and end in the deS solution at X = ∞, X = +∞, thus revealing the domination of the cosmological potential term [14,30,[32][33][34]38,39]. More importantly, we see that the solutions are attracted to the positive G half plane.…”

mentioning

confidence: 84%

What if Newton’s Gravitational Constant Was Negative?

2019

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In this work, we seek a cosmological mechanism that may define the sign of the effective gravitational coupling constant, G. To this end, we consider general scalar-tensor gravity theories as they provide the field theory natural framework for the variation of the gravitational coupling. We find that models with a quadratic potential naturally stabilize the value of G into the positive branch of the evolution and further, that de Sitter inflation and a relaxation to General Relativity is easily attained.

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“…However, we think that this very important subject needs to be discussed in more length. We want to make clear that the statement on the non-universality of the GR-de Sitter equilibrium point, 454 does not forbids the possible existence of exact de Sitter solutions for several choices of the self-interaction potential (see, for instance, Ref. 467).…”

Section: (Non)emergence Of the λCdm Phase From The Brans-dicke Cosmologymentioning

confidence: 99%

Selected topics in scalar–tensor theories and beyond

Quirós

2019

Int. J. Mod. Phys. D

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109

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Scalar fields have played an important role in the development of the fundamental theories of physics as well as in other branches of physics such as gravitation and cosmology. For a long time these escaped detection until 2012 year when the Higgs boson was observed for the first time. Since then alternatives to the general theory of relativity like the Brans-Dicke theory, scalar-tensor theories of gravity and their higher derivative generalizations -collectively known as Horndeski theories -have acquired renewed interest. In the present review we discuss on several selected topics regarding these theories, mainly from the theoretical perspective but with due mention of the observational aspect. Among the topics covered in this review we pay special attention to the following: 1) the asymptotic dynamics of cosmological models based in the Brans-Dicke, scalar-tensor and Horndeski theories, 2) inflationary models, extended quintessence and the Galileons, with emphasis in causality and stability issues, 3) the chameleon and Vainshtein screening mechanisms that may allow the elusive scalar field to evade the tight observational constraints implied by the solar system experiments, 4) the conformal frames conundrum with a brief discussion on the disformal transformations and 5) the role of Weyl symmetry and scale invariance in the gravitation theories. The review is aimed at specialists as well as at non-specialists in the subject, including postgraduate students.

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Brans-Dicke cosmology does not have theΛCDMphase as a universal attractor

Cited by 19 publications

References 83 publications

Intermediate accelerated solutions as generic late-time attractors in a modified Jordan-Brans-Dicke theory

Intermediate accelerated solutions as generic late-time attractors in a modified Jordan-Brans-Dicke theory

What if Newton’s Gravitational Constant Was Negative?

Selected topics in scalar–tensor theories and beyond

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