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

Lu, Jianbo; Li, Jiachun; Guo, Hui; Zhuang, Zhitong; Zhao, Xin

doi:10.1016/j.physletb.2020.135985

Cited by 11 publications

(5 citation statements)

References 134 publications

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“…1) Basic equations for GBD modified theory in both the metric formalism and the Palatini formalism Some problems on f(R) theory have been found in some reference [8], such as the inconsistent problem of γ between the theoretical value and the observational value (here γ is the parametrized post-Newtonian parameter). The f(R) theory can be extended by considering some methods, such as the f(G) theory (adding the higher-order terms) [9] [10], the GBD theory [47] [48] [49], etc. In this part, we apply the geometric diagnostic methods to distinguish the different formalisms of GBD modified theory.…”

Section: The Geometrical Diagnostics For Gbd Theory With the Differen...mentioning

confidence: 99%

Geometrical Diagnostics for Modified Gravitational Theory with the Different Formalisms

Lu¹,

Xu²,

Wang³

et al. 2022

JHEPGC

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Geometrical diagnostic methods were often applied to distinguish the gravitational models. But it is scarce to investigate the differences between the different formalisms of modified gravitational theories (e.g. the metric formalism and the Palatini formalism). In this paper, we discriminate the gravitational theory with the different formalisms by using the geometrical diagnostic methods. For a considered modified theory of gravity (e.g. the f(R) theory or GBD theory), we can see that the difference between the two formalisms is remarkable according to the diagnostic results. And relative to the ΛCDM model, there are more deviations in metric formalism than those in Palatini formalism, according to the {r, s} diagnostic. Given that the GBD (generalized Brans-Dicke theory) is a time-variable Newton gravitational constant (VG) theory, the differences between the VG theory and the constant-G theory are studied. It indicates that the variation of Newton's gravitational constant could induce notable effects on geometrical quantities (e.g. r, s and q) in both metric formalism and Palatini formalism.

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Section: The Geometrical Diagnostics For Gbd Theory With the Differen...mentioning

confidence: 99%

Geometrical Diagnostics for Modified Gravitational Theory with the Different Formalisms

Lu¹,

Xu²,

Wang³

et al. 2022

JHEPGC

Self Cite

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“…The six independent variables, P 1 , ..., P 6 can define six basic polarization modes according to the geodesic deviation equation (38). Taking P 1 , ..., P 6 as the monochromatic plane wave solutions and bring (39) into Eq.…”

Section: Polarization Modes Of Gravitational Wavesmentioning

confidence: 99%

“…In Palatini formalism, the polarization modes of gravitational waves have been studied in some gravitational theories, such as Holst-f (R) [37] and generalized Brans-Dicke theory [38]. In Ref.…”

Section: Introductionmentioning

confidence: 99%

Polarization Modes of Gravitational Waves in Palatini Horndeski theory

Dong,

Liu

2021

Preprint

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In this paper, the polarization modes of gravitational waves in Horndeski gravity are studied under the Palatini formalism. After obtaining the linearized equation of perturbations in Minkowski background, we find that the polarization modes of gravitational waves depend on the selection of the theoretical parameters. The polarization modes can be divided into quite rich cases by parameters. In all cases of parameter selection, there are + and × modes propagating at the speed of light but no vector modes. The only difference from general relativity is scalar modes, especially the scalar degrees of freedom can be 0, 1 or 2 in different cases. The appropriate parameter cases can be expected to be selected in the detection of gravitational wave polarization modes by Lisa, Taiji and TianQin in the future.

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“…The exploration of modified theories of gravity remain a hot topic in current research of gravitational physics. As one type of modified gravity theory, the Generalized Brans-Dicke (GBD) theory has been studied in cosmology, gravitational wave physics, and other fields [9][10][11]. In this paper we will explore some issues in the framework of GBD theory.…”

Section: Introductionmentioning

confidence: 99%

Properties of Spherically Symmetric Black Hole in the Framework of GBD Modified Gravitational Theory

Xu¹,

Li²,

Yang³

et al. 2023

Preprint

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The many problems faced by the theory of general relativity (GR) have always motivated us to explore the modified theory of GR. Considering the importance of studying the black hole (BH) entropy and its correction in gravity physics, we study the correction of thermodynamic entropy for a kind of spherically symmetric black holes under the generalized Brans-Dicke (GBD) theory of modified gravity. We derive and calculate the entropy and heat capacity. It is found that when the value of event horizon radius~$r_+$~is small, the effect of the entropy correction term on the entropy is very obvious, while for larger values~$r_+$~, the contribution of the correction term on entropy can be almost ignored. In addition, we can observe that as the radius of the event horizon increases, the heat capacity of BH in GBD theory will change from a negative value to a positive value, indicating that there is a phase transition in black holes. Given that studying the structure of geodesic lines is important for exploring the physical characteristics of a strong gravitational field, we also investigate the stability of the geodesic motion of particles in static spherically symmetric BHs within the framework of GBD theory. Concretely, we analyzes the dependence of the innermost stable circular orbit on model parameters. Also, the geodesic deviation equation is also applied to investigate the stable circular orbit of particles in GBD theory. The conditions for the stability of BH solution and the limited range of radial coordinates required to achieve stable circular orbit motion are given. Finally, we show the locations of stable circular orbits, and obtain the angular velocity, the specific energy and angular momentum of the particles which move in circular orbits.

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

Cited by 11 publications

References 134 publications

Geometrical Diagnostics for Modified Gravitational Theory with the Different Formalisms

Geometrical Diagnostics for Modified Gravitational Theory with the Different Formalisms

Polarization Modes of Gravitational Waves in Palatini Horndeski theory

Properties of Spherically Symmetric Black Hole in the Framework of GBD Modified Gravitational Theory

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