Hybrid theory of gravity

Kan, Nahomi; Maki, Taisuke; Shiraishi, Kiyoshi

doi:10.1103/physrevd.94.084001

Cited by 8 publications

(8 citation statements)

References 32 publications

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“…The present results have been obtained for the particular version of GSG presented in [11,12,15,16]. It would be of interest to find out how they can change in its more general formulations discussed in [30][31][32], which can be a subject for future studies. Thus, it seems possible that some more complex action than (4), containing a function of two variables, φ and w, can lead to a scalar geometric theory compatible with all appropriate observational constraints.…”

Section: Discussionmentioning

confidence: 92%

On variations of G in the geometric scalar theory of gravity

Бронников

2020

Eur. Phys. J. C

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We analyze the possible variability of the effective Newtonian gravitational constant $$G_{\mathrm{N}}$$GN in space and time in the framework of the geometric scalar theory of gravity suggested by Novello et al. (JCAP 06:014, 2013). Spatial variations of $$G_{\mathrm{N}}$$GN in the Solar system are shown to have orders of magnitude detectable by modern instruments. As to variations of $$G_{\mathrm{N}}$$GN with cosmological time, it is shown (at least for the particular formulation of the theory discussed in the original paper and the corresponding cosmological models) that these variations are more rapid than is allowed by observations.

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Section: Discussionmentioning

confidence: 92%

On variations of G in the geometric scalar theory of gravity

Бронников

2020

Eur. Phys. J. C

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“…Therefore, an important remaining question is how large graviton mass is possible from the theoretical and observational points of view. From the theoretical point of view, we should start from more fundamental theory in which a bigravity theory is reduced as a low-energy effective theory [47][48][49]. We hope that the hierarchy between the graviton mass and an effective cosmological constant to explain both dark sectors will be solved in such a fundamental theory.…”

Section: Discussionmentioning

confidence: 99%

Dark matter in ghost-free bigravity theory: From a galaxy scale to the universe

Aoki

Maeda

2014

Phys. Rev. D

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We study the origin of dark matter based on the ghost-free bigravity theory with twin matter fluids. The present cosmic acceleration can be explained by the existence of graviton mass, while dark matter is required in several cosmological situations [the galactic missing mass, the cosmic structure formation and the standard big-bang scenario (the cosmological nucleosynthesis vs the CMB observation)]. Assuming that the Compton wavelength of the massive graviton is shorter than a galactic scale, we show the bigravity theory can explain dark matter by twin matter fluid as well as the cosmic acceleration by tuning appropriate coupling constants.

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“…where R 1 and R 2 are given by (217) and, in terms of the variables x, y, the denominator 3αH 2 is given by (215). Hence, for the effective EOS in the general caseunspecified ǫ -we get:…”

Section: Phantom Barrier Crossing: General Analysismentioning

confidence: 99%

Selected topics in scalar–tensor theories and beyond

Quirós

2019

Int. J. Mod. Phys. D

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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Hybrid theory of gravity

Cited by 8 publications

References 32 publications

On variations of G in the geometric scalar theory of gravity

On variations of G in the geometric scalar theory of gravity

Dark matter in ghost-free bigravity theory: From a galaxy scale to the universe

Selected topics in scalar–tensor theories and beyond

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