Brans-Dicke scalar field as a chameleon

Das, Sudipta; Banerjee, Narayan

doi:10.1103/physrevd.78.043512

Cited by 123 publications

(82 citation statements)

References 61 publications

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“…With the use of the conservation equation ∇ ν (ρu ν ) = 0, one obtains the equation of motion of massive test particles as (28) can also be derived from the variational principle δ 1 + dp/ρ √ g µν u µ u ν ds = 0. Models with scalar field-matter coupling were considered in the framework of the Brans-Dicke theory [20], with the action of the model given by…”

Section: Models With Nonminimal Matter-scalar Field Couplingmentioning

confidence: 99%

Extendedf(R,Lm)gravity with generalized scalar field and kinetic term dependences

Harkó¹,

Lobo²,

Minazzoli³

2013

Phys. Rev. D

112

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We generalize previous work by considering a novel gravitational model with an action given by an arbitrary function of the Ricci scalar, the matter Lagrangian density, a scalar field and a kinetic term constructed from the gradients of the scalar field, respectively. The gravitational field equations in the metric formalism are obtained, as well as the equations of motion for test particles, which follow from the covariant divergence of the stress-energy tensor. Specific models with a nonminimal coupling between the scalar field and the matter Lagrangian are further explored. We emphasize that these models are extremely useful for describing an interaction between dark energy and dark matter, and for explaining the late-time cosmic acceleration.

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Section: Models With Nonminimal Matter-scalar Field Couplingmentioning

confidence: 99%

Extendedf(R,Lm)gravity with generalized scalar field and kinetic term dependences

Harkó¹,

Lobo²,

Minazzoli³

2013

Phys. Rev. D

112

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“…Obviously the other option is to look for the modification of GR which allows the cosmic acceleration without introducing any exotic component. Scalar-tensor theories (Bertolami & Martins 2000;Banerjee & Paovn 2001a,b;Sen & Sen 2001;Mota & Barrow 2004a,b;Das & Banerjee 2008), f (R) gravity theory (Capozziello et al 2003;Carroll et al 2004;Vollick 2003;Nojiri & Odintsov 2003;Carroll et al 2005;Mena et al 2006;Nojiri & Odintsov 2006;Das et al 2006;Nojiri & Odintsov 2007a,b, 2009), different higher dimensional gravity theories (Deffayet et al 2002 Though different theoretical approaches are there to explain the phenomenon of cosmic acceleration, till now none of them is definitely known as the appropriate one. The present trend of modelling of late time cosmic acceleration is called reconstruction where the model is built up by taking the observational data directly into account.…”

Section: Introductionmentioning

confidence: 99%

Acceleration of the universe: a reconstruction of the effective equation of state

Mukherjee

2016

Mon. Not. R. Astron. Soc.

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The present work is based upon a parametric reconstruction of the effective or total equation of state in a model for the universe with accelerated expansion. The constraints on the model parameters are obtained by maximum likelihood analysis using the supernova distance modulus data, observational Hubble data, baryon acoustic oscillation data and cosmic microwave background shift parameter data. For statistical comparison, the same analysis has also been carried out for the wCDM dark energy model. Different model selection criteria (Akaike information criterion (AIC)) and (Bayesian Information Criterion (BIC)) give the clear indication that the reconstructed model is well consistent with the wCDM model. Then both the models (w ef f (z) model and wCDM model) have also been presented through (q 0 ,j 0 ) parameter space. Tighter constraint on the present values of dark energy equation of state parameter (w DE (z = 0)) and cosmological jerk (j 0 ) have been achieved for the reconstructed model.

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“…We will focus on a few concrete models where Chameleon screening arises, but the phenomenon is fairly general and has been extensively studied beyond the contexts we discuss [275][276][277][278][279][280][281][282][283][284][285][286][287]. For example, Chameleons have been extended to K-essence theories [288], used for inflation [289,290] and embedded in supersymmetry and string theory [291][292][293][294][295].…”

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confidence: 99%

Beyond the cosmological standard model

et al. 2015

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After a decade and a half of research motivated by the accelerating universe, theory and experiment have a reached a certain level of maturity. The development of theoretical models beyond Λ or smooth dark energy, often called modified gravity, has led to broader insights into a path forward, and a host of observational and experimental tests have been developed. In this review we present the current state of the field and describe a framework for anticipating developments in the next decade. We identify the guiding principles for rigorous and consistent modifications of the standard model, and discuss the prospects for empirical tests.We begin by reviewing recent attempts to consistently modify Einstein gravity in the infrared, focusing on the notion that additional degrees of freedom introduced by the modification must "screen" themselves from local tests of gravity. We categorize screening mechanisms into three broad classes: mechanisms which become active in regions of high Newtonian potential, those in which first derivatives of the field become important, and those for which second derivatives of the field are important. Examples of the first class, such as f (R) gravity, employ the familiar chameleon or symmetron mechanisms, whereas examples of the last class are galileon and massive gravity theories, employing the Vainshtein mechanism. In each case, we describe the theories as effective theories and discuss prospects for completion in a more fundamental theory. We describe experimental tests of each class of theories, summarizing laboratory and solar system tests and describing in some detail astrophysical and cosmological tests. Finally, we discuss prospects for future tests which will be sensitive to different signatures of new physics in the gravitational sector.The review is structured so that those parts that are more relevant to theorists vs. observers/experimentalists are clearly indicated, in the hope that this will serve as a useful reference for both audiences, as well as helping those interested in bridging the gap between them.

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Brans-Dicke scalar field as a chameleon

Cited by 123 publications

References 61 publications

Extendedf(R,Lm)gravity with generalized scalar field and kinetic term dependences

Extendedf(R,Lm)gravity with generalized scalar field and kinetic term dependences

Acceleration of the universe: a reconstruction of the effective equation of state

Beyond the cosmological standard model

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