On the "Einstein-Gauss-Bonnet Gravity in Four Dimension"

Cao, Li-Ming; Wu, Liang-Bi

doi:10.48550/arxiv.2103.09612

Cited by 8 publications

(8 citation statements)

References 11 publications

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“…Consequently several works appear in the literature which includes formulation of cosmological solutions [15,16], spherical black hole solutions [17][18][19][20], solutions of star-like objects [21], radiating and collapsing solutions [22,23], extending to more higher-curvature Lovelock theories [24], thermodynamic behaviour of black holes in such theories [25][26][27][28] and the gravitational and physical properties of these objects [29][30][31][32][33][34][35][36][37][38][39][40]. Despite all these, the regularization scheme used in this novel four dimensional Einstein-Gauss-Bonnet (4D-EGB) theory [14] was found to be inconsistent on several grounds [41][42][43][44][45][46][47][48][49], which led to the development of different versions of regularized (consistent) 4D-EGB theories [16,[50][51][52][53][54].…”

Section: Introductionmentioning

confidence: 99%

Naked singularity in 4D Einstein-Gauss-Bonnet novel gravity: Echoes and (in)-stability

Chowdhury,

Devi,

Chakrabarti

2022

Preprint

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We study the stability of an asymptotically flat, static, spherically symmetric naked singularity spacetime in the novel four dimensional Einstein-Gauss-Bonnet (EGB) gravity. The four dimensional EGB black hole for large enough values of the coupling parameter leads to such a naked singularity. The stability and the response of the spacetime is studied against the perturbations by test scalar, electromagnetic and Dirac fields and the time evolution of these perturbations were observed numerically. Implementing a null Dirichlet boundary condition near the singularity, we observed that for l = 1 modes of scalar, electromagnetic perturbation and l = 0, 1 modes of Dirac perturbation the time-domain profile give rise to distinct echoes. However, as the coupling constant is increased, the echoes align and the QNM structure of the 4D-EGB naked singularity-spacetime becomes prominent. For higher values of the multipole number, the spacetime becomes unstable, thereby restricting the parameter space for the coupling parameter.

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Section: Introductionmentioning

confidence: 99%

Naked singularity in 4D Einstein-Gauss-Bonnet novel gravity: Echoes and (in)-stability

Chowdhury,

Devi,

Chakrabarti

2022

Preprint

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“…One is based on the the linearized equations of motion. The well-posed formulation in Horndeski and Lovelock gravity at the perturbative level has been studied in [12][13][14][15][16]. Certainly, it is important for us to find a well-posed, nonperturbative formulation in general relativity or modified gravities.…”

Section: Introductionmentioning

confidence: 99%

A Note on the Strong Hyperbolicity of $f(R)$ Gravity with Dynamical Shifts

Cao,

2021

Preprint

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The well-posedness of the gravitational equations of f (R) gravity are studied in this paper. Three formulations of the f (R) gravity with dynamical shifts (which are all based on the Arnowitt-Deser-Misner (ADM) formalism of the equations) are investigated. These three formulations are all proved to be strongly hyperbolic by pseudodifferential reduction. The first one is the Baumagarte-Shapiro-Shibata-Nakamura (BSSN) formulation with the so-called "hyperbolic K-driver" condition and the "hyperbolic Gamma driver" condition. The second one is the ADM formulation with modified harmonic gauge conditions. We find that the equations are not strong hyperbolic in traditional Z4 formulation for f (R) gravity. So, in the third formulation, we improve the Z4 formulation, and show these equations are strong hyperbolic with modified harmonic gauge conditions.

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“…Also, many works has been done to generalize the idea to higher/lower dimensions, relations to other theories and also its quantum aspects of the theory [14]. For example, in [15], the authors showed that in order to have a well-defined linearized theory the metric should be locally conformally flat. Also, many works have been done to constraint the new re-scaled Gauss-Bonnet parameter from observational data [16].…”

Section: Introductionmentioning

confidence: 99%

Anisotropy in constraint 4D Gauss-Bonnet gravity

Shahidi,

Khosravi

2021

Preprint

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Recently a new 4D Einstein-Gauss-Bonnet theory has been introduced [Phys. Rev. Lett. 124 (2020) 081301] with a serious debate that it does not possess a covariant equation of motion in 4D. In this note, we will present a new proposal to make this happen, by introducing a Lagrange multiplier to the action which eliminates the higher dimensional term from the equation of motion. The theory has then a covariant 4D equation of motion which is useful to study the less symmetric metrics. On top of FRW universe, the constraint theory is equivalent to the original 4D Einstein-Gauss-Bonnet gravity. We will also consider the anisotropy of the model and compare the theory with observational data. We will see that the theory becomes non-conservative and the matter density abundance falls more rapidly at larger redshifts compared to the conservative matter sources.

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On the "Einstein-Gauss-Bonnet Gravity in Four Dimension"

Cited by 8 publications

References 11 publications

Naked singularity in 4D Einstein-Gauss-Bonnet novel gravity: Echoes and (in)-stability

Naked singularity in 4D Einstein-Gauss-Bonnet novel gravity: Echoes and (in)-stability

A Note on the Strong Hyperbolicity of $f(R)$ Gravity with Dynamical Shifts

Anisotropy in constraint 4D Gauss-Bonnet gravity

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