Linearized modified gravity theories with a cosmological term: advance of perihelion and deflection of light

Özer, Hatice; Delice, Özgür

doi:10.48550/arxiv.1708.05900

Cited by 5 publications

(5 citation statements)

References 70 publications

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“…A third possibility, of course, is to consider more general potentials, but they do not have a direct interpretation of a CC term as in the original GR action with a cosmological term, see e.g. [462][463][464][465]. Let us briefly explain why.…”

Section: Cosmological Constant and Vacuum Energy In Bd Theorymentioning

confidence: 99%

Brans–Dicke Gravity with a Cosmological Constant Smoothes Out ΛCDM Tensions

Peracaula

Gómez-Valent

Pérez

et al. 2019

ApJL

132

138

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We analyze Brans-Dicke gravity with a cosmological constant, Λ, and cold dark matter (BD-ΛCDM for short) in the light of the latest cosmological observations on distant supernovae, Hubble rate measurements at different redshifts, baryonic acoustic oscillations, large scale structure formation data, gravitational weak-lensing and the cosmic microwave background under full Planck 2015 CMB likelihood. Our analysis includes both the background and perturbations equations. We find that BD-ΛCDM is observationally favored as compared to the concordance ΛCDM model, which is traditionally defined within General Relativity (GR). In particular, some well-known persisting tensions of the ΛCDM with the data, such as the excess in the mass fluctuation amplitude σ 8 and specially the acute H 0 -tension with the local measurements, essentially disappear in this context. Furthermore, viewed from the GR standpoint, BD-ΛCDM cosmology mimics quintessence at 3σ c.l. near our time.

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Section: Cosmological Constant and Vacuum Energy In Bd Theorymentioning

confidence: 99%

Brans–Dicke Gravity with a Cosmological Constant Smoothes Out ΛCDM Tensions

Peracaula

Gómez-Valent

Pérez

et al. 2019

ApJL

132

138

View full text Add to dashboard Cite

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“…For observational and theoretical motivations, several extended versions of the BD theory have been developed, such as adding a potential term to the original BD theory [35], assuming the coupling constant ω to be variable with respect to time [36,37], generalizing φ to be a function f (φ) in the coupling term φR [38,39], choosing a higher-dimension geometry in the BD theory [40], etc. The applications of these extended BD theories have been investigated widely, such as at the aspects of cosmology [41][42][43], weak-field approximation [44],…”

Section: Introductionmentioning

confidence: 99%

Linearized physics and gravitational-waves polarizations in the Palatini formalism of GBD theory

Guo

et al. 2020

Physics Letters B

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A generalized Brans-Dicke (GBD) theory in the framework of Palatini formalism are proposed in this paper. We derive the field equations by using the variational approach and obtain the linearized equations by using the weak-field approximation method. We show various properties of the geometrical scalar field in the Palatini-formalism of GBD theory: it is massless and sourcefree, which are different from the results given in the metric-formalism of GBD theory. Also, we investigate the polarization modes of gravitational waves (GWs) by using the the geodesic deviation method and the Newman-Penrose method in the Palatini-GBD theory. It is observed that there are three polarizations modes and four oscillation in the Palatini-GBD theory. Concretely, they are the two transverse tensor (+) and (×) standard polarization modes, and one breathing mode (with two oscillation). The results of GWs polarization in the Palatini-GBD theory are different from that in the metric-GBD theory, where there are four polarizations modes: the two standard tensorial modes (+ and ×), a scalar breathing mode, and a massive scalar mode that is a mix of the longitudinal and the breathing polarization. Comparing with the Palatini-f (R) theory and the General Relativity, we can see that the extra breathing mode of GWs polarization can be found in the Palatini-GBD theory. At last, the expression of the parameterized post Newton (PPN) parameter is derived, which could pass through the experimental test.

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“…For observational and theoretical motivations, several extended versions of the BD theory have been investigated and developed, such as adding a potential term to the original BD theory [32], assuming the coupling constant ω to be variable with respect to time [33,34], etc. The applications of these extended BD theories have been investigated widely, such as at the aspects of cosmology [35][36][37], weak-field approximation [38], observational constraints [39,40], and so on [41][42][43].…”

Section: Introductionmentioning

confidence: 99%

Linearized modified gravity theories and gravitational waves physics in the GBD theory

Wang

Zhao

2019

Physics Letters B

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The generalized Brans-Dicke (abbreviated as GBD) theory is obtained by replacing the Ricci scalar R in the original Brans-Dicke (BD) action with an arbitrary function f (R). Comparing with other theories, some interesting properties have been found or some problems existing in other theories could be solved in the GBD theory. For example, (1) the state parameter of geometrical dark energy in the GBD model can cross over the phantom boundary w = −1, without bearing the problems existing in the quintom model (e.g. the problem of negative kinetic term and the finetuning problem, etc);(2) f (R) theory is equivalent to the BD theory with a potential (BDV) with the couple parameter ω = 0, where the kinetic term of field in the equivalent BDV theory is absent.While the scalar fields in the GBD own the non-disappeared kinetic term, when one compares the GBD theory with the f (R) theory. In this paper, we continue to investigate the GBD theory. Using the method of the weak-field approximation, we explore the linearized physics in the GBD theory.The linearized equations of the gravitational field and two scalar fields are given. We investigate their solutions in the linearized theory for a point mass. It is shown that the problem of the γ (parametrized post-Newtonian parameter) value in the f (R) theory could be solved in the GBD theory, where the theoretical γ value in the GBD theory can be consistent with the observational results. At last, we study the gravitational waves physics in the vacuum for the GBD theory. It is found that the gravitational radiation in the GBD theory has new freedoms beyond the two standard modes in the general relativity theory.

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Linearized modified gravity theories with a cosmological term: advance of perihelion and deflection of light

Cited by 5 publications

References 70 publications

Brans–Dicke Gravity with a Cosmological Constant Smoothes Out ΛCDM Tensions

Brans–Dicke Gravity with a Cosmological Constant Smoothes Out ΛCDM Tensions

Linearized physics and gravitational-waves polarizations in the Palatini formalism of GBD theory

Linearized modified gravity theories and gravitational waves physics in the GBD theory

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