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REVIEW 3 major objections 5 minor 58 references

Universal cosmological solutions in Lovelock gravity

T0 review · 3 major / 5 minor · reviewed 2026-08-11 · deepseek-v4-flash

Pith's one-line read The paper aims to establish that Lovelock gravity's generalized Friedmann equations hold for any polynomial order and dimension and admit universal vacuum solutions that expand without a cosmological constant.

desk verdict Useful Lovelock Friedmann reformulation, but the universal vacuum solutions are known constant-curvature vacua with an unstated existence condition. read the letter →

arxiv 2412.18814 v1 pith:SEOFQ5VP submitted 2024-12-25 gr-qc

classification gr-qc MSC 83D0583F0583C1583E15 PACS 04.20.Jb04.50.Kd
keywords LovelockgravityFriedmannequationscosmologicalvacuumsolutionsdeSitterexpansiondarkenergyhigher-dimensionalGauss-BonnetindependentRiemanntensorcomponents
topics Dark Energy
open problems Dark Energy
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

This paper aims to show that Lovelock gravity, a higher-order generalization of Einstein gravity, has Friedmann equations valid for any Lovelock polynomial order and any spacetime dimension. The central claim is that these equations admit vacuum solutions with no matter and no cosmological constant: flat universes have constant-Hubble (anti-)de Sitter expansion, while pressure-free open and closed universes have scale factors built from sinh and cosh of the same algebraic root. If correct, accelerated expansion is built into Lovelock gravity rather than requiring a separate dark-energy sector. The paper also provides a practical toolkit, writing the field equations directly in terms of the two independent Riemann components of a Friedmann-Lemaitre-Robertson-Walker metric.

What carries the argument

The load-bearing object is the decomposition of the Friedmann-Lemaitre-Robertson-Walker Riemann tensor into two independent components, $f_1=\dot a^2/a^2+k/a^2$ and $f_2=\ddot a/a$, extending the independent Riemann-component method to $N$ dimensions. With this decomposition, each Lovelock order contributes terms $\alpha_i f_1^{i-1}({}^{(i)}k_{11}f_1+{}^{(i)}k_{12}f_2)$ to the pressure equation and $\alpha_i f_1^i{}^{(i)}k_{21}$ to the density equation. The algebraic identity ${}^{(i)}k_{11}+{}^{(i)}k_{12}-{}^{(i)}k_{21}=0$ lets the two equations combine into a single evolution equation in which the Lovelock correction appears as an extra term, and setting that term to zero gives the new vacuum roots. For the pressure-free open and closed universes, the ansatz $z^2=a^2(1+C_1a^2)$ for open and $z^2=a^2(C_1a^2-1)$ for closed collapses the full equation into the polynomial $\sum_{i=1}^n\alpha_i{}^{(i)}k_{12}C_1^i/i=0$, whose root $C_1$ supplies the $\sinh$ and $\cosh$ solutions.

What would settle it

Choose a Lovelock order and coupling set for which the polynomial $2-N+\sum_{i=2}^n\alpha_i{}^{(i)}k_{12}C_1^{i-1}/i=0$ has no real root, then numerically integrate the full pressure-free open-universe equations (34a)-(34b). If an expanding pressure-free solution still exists, the ansatz-based solution (47) is not universal and the reduction to (40) has dropped a branch.

Watch

Extended reading notes

Core claim

On the paper's own terms, the central discovery is that the Lovelock field equations for an $N$-dimensional Friedmann-Lemaitre-Robertson-Walker metric reduce to the compact pair (19a)-(19b), in which the only curvature data are the two independent Riemann tensor components $f_1=\dot a^2/a^2+k/a^2$ and $f_2=\ddot a/a$. From these the author derives the generalized Friedmann equations (20a)-(20b) and identifies two classes of universal vacuum solutions: Type II solutions that reproduce the ordinary general-relativity vacuum ($a=\text{const}$ for flat, $a=t$ for open), and Type I solutions exclusive to Lovelock gravity. The Type I solutions are the flat vacuum (anti-)de Sitter expansion with $H$ a constant root of (29), and the pressure-free open and closed universes $a=\sinh(\sqrt{C_1}t)/\sqrt{C_1}$ and $a=\cosh(\sqrt{C_1}t)/\sqrt{C_1}$, where $C_1$ is a root of the same algebraic polynomial (43). The stated conclusion is that Lovelock cosmology provides dark-energy-like behavior by design, without an explicit cosmological constant.

Load-bearing premise

The derivation's load-bearing premise is that the ansatz $z^2=a^2(1+C_1a^2)$ for the open universe, and its closed-universe analogue, does not discard any physical branch when the equations are manipulated by dividing by $z$ and by sums of Lovelock terms, and that a real root $C_1$ of the polynomial exists for the chosen couplings.

Editorial extensions

If this is right

  • If the generalized Friedmann equations are correct, every Lovelock theory of order $n>1$ has flat vacuum (anti-)de Sitter solutions, so vacuum expansion is a generic feature rather than a fine-tuned one.
  • The open- and closed-universe pressure-free solutions (47) and (59) reproduce the scale-factor evolution that in general relativity requires an equation of state $p=-\rho$, meaning Lovelock gravity can mimic dark energy without a cosmological constant.
  • Setting $N=4$, $n=1$, $\alpha_i=0$ in (20a)-(20b) recovers the standard Friedmann equations, so the new equations contain general relativity as a limiting case.
  • The Type II vacuum solutions $a=\text{const}$ and $a=t$ are shared with general relativity, while the Type I solutions are new, giving a clean classification of vacuum cosmology in Lovelock gravity.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • Inference: if the flat vacuum root (29) is real for observationally allowed couplings, the same mechanism could explain both early-universe inflation and late-time acceleration from one geometric sector, with no separate scalar field.
  • Inference: the two-component reduction used here should apply to other spherically symmetric metrics, since the paper notes the Lovelock tensor depends only on $f_1$ and $f_2$; this is a direct testable extension.
  • Inference: the closed-universe solution (59) has no $a(0)=0$ limit, suggesting that a big-bang starting point in closed Lovelock cosmology would require a different branch or a phase transition, an issue the paper does not address.
  • Inference: if observations ever fix $N$, $n$, and $\alpha_i$, the algebraic root $C_1$ from (43) becomes a quantitative consistency test of Lovelock gravity against the measured expansion history.
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Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Referee Report

3 major / 5 minor

Summary. This paper develops a component-based derivation of Friedmann-type equations for Lovelock gravity in N dimensions, based on the observation that for FRWL metrics the Riemann tensor has only two independent components. The author obtains generalized Friedmann equations (19a)-(20b), identifies a flat vacuum solution (29), and constructs pressure-free solutions for open and closed universes, Eqs. (47) and (59), claimed to be universal in the sense of being valid for any Lovelock polynomial order, dimension, and coupling constants. The paper further argues that these solutions provide a built-in dark-energy-like behavior without a cosmological constant.

Significance. The component method is potentially useful and the explicit tabulated Friedmann equations for low orders and dimensions could serve as a practical reference. If the technical issues are corrected, the approach could give a compact derivation of known and new Lovelock FRW equations, and the explicit vacuum solutions would be a useful addition to the Lovelock-cosmology literature. However, the claims of universality are currently not backed by the equations as written: the coefficient indexing in the polynomial sums is internally inconsistent, and the 'universal' solutions require real-root conditions that are never stated.

major comments (3)
  1. [Friedmann equations, Eqs. (19a)-(20b)] In Eqs. (19a)-(19b) and (20a)-(20b), the coefficients inside the sums over i=2..n are written as (n)k11, (n)k12, and (n)k21, but each Lovelock order i contributes its own coefficients (i)k11, (i)k12, and (i)k21 defined by (17a)-(17c) with n replaced by i. The equations as written are therefore only valid for a pure Lovelock term of a single order, not for the polynomial action (7). The same improper indexing appears in Eqs. (24), (27), (40), (42), and (43), so the derivation of the universal solutions (47) and (59) is not supported by the stated action.
  2. [Universal solutions, Eqs. (43), (47), (59)] The paper presents (47) and (59) as universal vacuum solutions for any Lovelock couplings, but never requires Eq. (43) to have a real root C1 of the sign compatible with the ansaetze (41) and (54). This is not a minor caveat: for a pure cubic Lovelock theory with N=8, n=3, alpha2=0, alpha3=+1, Eq. (43) becomes -6-720 C1^2=0 and has no real solution, so neither (47) nor (59) is a real scale factor. For Gauss-Bonnet with N=5 and alpha2>0, Eq. (43) gives C1<0, which makes the closed solution (59) complex and the open solution (47) oscillatory rather than the advertised hyperbolic expansion. The wording 'universal' is therefore an overstatement; the paper should state a root-existence and sign condition, or restrict the claim to parameter regions where such a real root exists.
  3. [Friedmann equations, Eq. (22)] Equation (22) uses the N=2n+1 simplification k11=0 and k12=k21 for every term in the sum over i, but this simplification holds only for the top-order term i=n. For lower-order terms, N is not equal to 2i+1, so (i)k11 does not vanish and (i)k12 is not equal to (i)k21. Consequently Eq. (22) does not represent the Friedmann equations for a generic Lovelock polynomial even in the special dimension N=2n+1; it is valid only for pure Lovelock with a single term of order n.
minor comments (5)
  1. [Open universe, Eq. (44)] Equation (44) writes a = ±(1/sqrt(C1)) sinh(C2-eta), but the solution of the ansatz (41) with z^2=a^2(1+C1 a^2) is a = ±1/(sqrt(C1) sinh(C2-eta)) (a cosecant, not a sine). The final cosmic-time expression (47) appears recoverable after the time reparametrization, but the intermediate equation and the t-integral leading to (45) need to be corrected or explained.
  2. [Appendix] The appendix proof uses undefined symbols (for example r, g22, phi_alpha) and contains several typographical errors that make the derivation hard to check; a clean version of the proof would improve the reliability of the central claim (6a)-(6b).
  3. [Universal solutions section] The types 'Type I' and 'Type II' are used informally and could be defined more precisely; in particular, the claim that Type II solutions do not depend on N, n, or alpha_i should be stated explicitly for each example.
  4. [Lovelock gravity section] The assertion that only Lovelock gravities with N >= 2n+1 are physically significant is stated with reference [13] but no explanation; a brief justification would be helpful for the reader.
  5. [References] Some bibliographic entries are incomplete or contain errors (e.g., [25] lacks volume and page information); a careful final reference check is advised.

Circularity Check

0 steps flagged · score 0.0 of 10

No significant circularity: the generalized Friedmann equations and the universal solutions follow algebraically from the Lovelock action and the FRW ansatz.

full rationale

The derivation chain is self-contained: the Lovelock field equations (7) with the FRW metric (3) are reduced to the two-component expressions (19a)-(19b), written as (20a)-(20b), and the flat/open/closed solutions follow by substituting the stated ansatze and solving the algebraic condition (43). No parameter is fitted to data and no 'prediction' is statistically forced. The solution families (47) and (59) are parameterized by C1 defined as a root of (43); if that polynomial has no real root of the required sign for some N, n, and couplings, then the corresponding real solution does not exist, which is a domain-of-validity limitation rather than circularity. The only self-citation, reference [41], is an introductory citation about distance measurements and is not load-bearing. The statement that Lovelock cosmology provides 'Dark Energy behavior by design' is an interpretive label for extra vacuum terms generated by the free Lovelock couplings, not a fitted input renamed as a prediction. No imported uniqueness theorem, no ansatz smuggled via citation, and no renaming of a known result as a new one are present.

Assumptions & free parameters 3 free parameters · 4 assumptions · 0 invented entities

The central claims rest on the Lovelock action with arbitrary couplings and on the FRW ansatz. No new particles, fields, or additional entities are introduced. The 'dark energy component' is an interpretation of the Lovelock terms, not an independent entity.

free parameters (3)
  • alpha_i
    Lovelock coupling constants for orders i=2..n. They are free parameters of the theory and determine the roots H and C1. No values are derived or fitted.
  • N
    Spacetime dimension, treated as arbitrary. The paper sets no specific N except in examples.
  • n
    Lovelock polynomial order, treated as arbitrary. The paper requires N >= 2n+1, citing prior literature.
assumptions (4)
  • domain assumption The FRW metric ansatz (3) with spatial curvature k is assumed for the cosmological spacetime.
    All derivations start from the FRW metric; the paper does not consider anisotropic or inhomogeneous spacetimes.
  • domain assumption The Lovelock action with field equations (7) and the generalized Ricci/Riemann constructions (9)-(11) are assumed.
    The paper builds directly on the Lovelock Lagrangian and its field equations, taking them as the theory to analyze.
  • ad hoc to paper The algebraic identities k22=0 and k11+k12-k21=0 are used to simplify the equations.
    These identities are derived in the paper from combinatorial relations such as 2(n-1) C(N-2,2(n-1)) = (N-2) C(N-3,2n-3). They are stated rather than proven in full detail.
  • domain assumption A real root of the polynomial (43) or (29) exists for the chosen Lovelock couplings.
    The solutions (47), (59), and Theorem 1 require a real C1 or H. The paper does not discuss conditions on alpha_i for real positive roots.

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Cite this review

Pith. "Pith review of Universal cosmological solutions in Lovelock gravity." pith.science (2026). https://pith.science/paper/SEOFQ5VP

@misc{pith2026241218814,
  author       = {Pith},
  title        = {Pith review of: Universal cosmological solutions in Lovelock gravity},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/SEOFQ5VP}},
  note         = {Machine review of arXiv:2412.18814}
}
read the original abstract

This paper explores the Friedmann field equations within the framework of Lovelock gravity, a natural extension of Einstein's gravity, focusing on both flat and open universes. Utilizing an approach based on independent Riemann tensor components, we derive generalized Friedmann equations for Lovelock gravity and categorize the solutions into Type I and Type II types. We identify additional vacuum solutions in a flat universe and present a comprehensive solution for a pressure-free scenario in an open universe, both unique to Lovelock gravity. These findings provide new insights into the cosmological implications of Lovelock gravity and offer a foundation for further exploration into the universe's evolutionary trajectory.

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Works this paper leans on

58 extracted references · 58 canonical work pages

  1. [1]

    Middleton

    Keith Andrew, Brett Bolen, and Chad A. Middleton. Soluti ons of higher dimensional gauss–bonnet frw cosmology. Gen. Relativ. Gravit. , 39(12):2061, 2007

  2. [2]

    Santill´ an

    Juan Manuel Armaleo, Juliana Osorio Morales, and Osvald o P. Santill´ an. Gauss-bonnet models with cosmological constant and non zero spatial curv ature in d=4. Eur. Phys. J. C , 78(2):85, 2018

  3. [3]

    Black hole in three-dimensional spacetime

    M´ aximo Ba˜ nados, Claudio Teitelboim, and Jorge Zanell i. Black hole in three-dimensional spacetime. Phys. Rev. Lett. , 69:1849–1851, Sep 1992

  4. [4]

    Dimensionally continued black holes

    M´ aximo Ba˜ nados, Claudio Teitelboim, and Jorge Zanelli. Dimensionally continued black holes. Phys. Rev. D , 49:975–986, Jan 1994

  5. [5]

    Generalized charged nariai solutions i n arbitrary even dimensions with multiple 17 magnetic charges

    Carlos Batista. Generalized charged nariai solutions i n arbitrary even dimensions with multiple 17 magnetic charges. Gen. Relativ. Gravit. , 48(12):160, Nov 2016

  6. [6]

    A compar ative study between egb gravity and gtr by modeling compact stars

    Piyali Bhar, Megan Govender, and Ranjan Sharma. A compar ative study between egb gravity and gtr by modeling compact stars. Eur. Phys. J. C , 77(2):109, 2017

  7. [7]

    G eneralized vaidya spacetime in lovelock gravity and thermodynamics on the apparent hori zon

    Rong-Gen Cai, Li-Ming Cao, Ya-Peng Hu, and Sang Pyo Kim. G eneralized vaidya spacetime in lovelock gravity and thermodynamics on the apparent hori zon. Phys. Rev. D , 78:124012, Dec 2008

  8. [8]

    Pure lovelock kasner metrics

    Xi´ an O Camanho, Naresh Dadhich, and Alfred Molina. Pure lovelock kasner metrics. Class. Quantum Grav., 32(17):175016, aug 2015

Show all 58 references
  1. [9]

    Canfora, A

    F. Canfora, A. Giacomini, S. A. Pavluchenko, and A. Topor ensky. Friedmann dynamics recovered from compactified einstein–gauss–bonnet cosmol ogy. Gravit. Cosmol. , 24(1):28, 2018

  2. [10]

    Cosmological perfect fluids in gauss–bonnet gravity

    Salvatore Capozziello, Carlo Alberto Mantica, and Luc a Guido Molinari. Cosmological perfect fluids in gauss–bonnet gravity. Int. J. Geom. Methods Mod. Phys. , 16(09):1950133, 2019

  3. [11]

    Limits on stel lar structures in lovelock theories of gravity

    Sumanta Chakraborty and Naresh Dadhich. Limits on stel lar structures in lovelock theories of gravity. Phys. Dark Universe , 30:100658, 2020

  4. [12]

    Brian Chilambwe, Sudan Hansraj, and Sunil D. Maharaj. N ew models for perfect fluids in egb gravity. Int. J. Mod. Phys. D , 24(07):1550051, 2015

  5. [13]

    Characterization of the lovelock grav ity by bianchi derivative

    Naresh Dadhich. Characterization of the lovelock grav ity by bianchi derivative. Pramana, 74(6):875–882, Jun 2010

  6. [14]

    Ghosh, and Sanjay Jhingan

    Naresh Dadhich, Sushant G. Ghosh, and Sanjay Jhingan. T he lovelock gravity in the critical spacetime dimension. Phys. Lett. B , 711(2):196 – 198, 2012

  7. [15]

    Ghosh, and Sanjay Jhingan

    Naresh Dadhich, Sushant G. Ghosh, and Sanjay Jhingan. G ravitational collapse in pure lovelock gravity in higher dimensions. Phys. Rev. D , 88:084024, Oct 2013

  8. [16]

    Co mpact objects in pure lovelock theory

    Naresh Dadhich, Sudan Hansraj, and Brian Chilambwe. Co mpact objects in pure lovelock theory. Int. J. Mod. Phys. D , 26(06):1750056, 2017

  9. [17]

    Naresh Dadhich, Sudan Hansraj, and Sunil D. Maharaj. Un iversality of isothermal fluid spheres in lovelock gravity. Phys. Rev. D , 93:044072, Feb 2016

  10. [18]

    Unifo rm density static fluid sphere in einstein-gauss-bonnet gravity and its universality

    Naresh Dadhich, Alfred Molina, and Avas Khugaev. Unifo rm density static fluid sphere in einstein-gauss-bonnet gravity and its universality. Phys. Rev. D , 81:104026, May 2010

  11. [19]

    Genera lized g¨ odel universes in higher dimensions and pure lovelock gravity

    Naresh Dadhich, Alfred Molina, and Josep M Pons. Genera lized g¨ odel universes in higher dimensions and pure lovelock gravity. Phys. Rev. D , 96:084058, Oct 2017. 18

  12. [20]

    Naresh Dadhich and Josep M. Pons. Probing pure lovelock gravity by nariai and bertotti- robinson solutions. J. Math. Phys. , 54(10):102501, 2013

  13. [21]

    Naresh Dadhich and Josep M. Pons. On static black holes s olutions in einstein and einstein- gauss-bonnet gravity with topology snx sn. Eur. Phys. J. C , 75(6):280, 2015

  14. [22]

    Pons, and Kartik Prabhu

    Naresh Dadhich, Josep M. Pons, and Kartik Prabhu. On the static lovelock black holes. Gen. Relativ. Gravit., 45(6):1131–1144, Jun 2013

  15. [23]

    Stephen C. Davis. Generalized israel junction conditi ons for a gauss-bonnet brane world. Phys. Rev. D , 67:024030, Jan 2003

  16. [24]

    D ´ ıaz, F

    R. D ´ ıaz, F. G´ omez, and M. Pinilla. De sitter brane-wor ld solution in 5-dimensional ein- stein–gauss–bonnet gravity. Gen. Relativ. Gravit. , 52(9):86, 2020

  17. [25]

    D ´ ıaz, F

    R. D ´ ıaz, F. G´ omez, M. Pinilla, and P. Salgado. Brane gravity in 4d from chern–simons gravity theory. Eur. Phys. J. C , 80(6):546

  18. [26]

    V.A. Fok. The researches of a.a. fridman on the einstein theory of gravitation. Sov. Phys. Usp., 6:473–474, 1964

  19. [27]

    Zong-Kuan Guo and Dominik J. Schwarz. Power spectra fro m an inflaton coupled to the gauss-bonnet term. Phys. Rev. D , 80:063523, Sep 2009

  20. [28]

    Gurses and Y

    M. Gurses and Y. Heydarzade. Flrw-cosmology in generic gravity theories. Eur. Phys. J. , 80(1061), 2020

  21. [29]

    Generalized spheroidal spacetimes in 5 -d einstein-maxwell-gauss-bonnet grav- ity

    Sudan Hansraj. Generalized spheroidal spacetimes in 5 -d einstein-maxwell-gauss-bonnet grav- ity. Eur. Phys. J. C , 77(8):557, 2017

  22. [30]

    Sudan Hansraj, Brian Chilambwe, and Sunil D. Maharaj. E xact egb models for spherical static perfect fluids. Eur. Phys. J. C , 75(6):277, 2015

  23. [31]

    Maharaj, and Brian Chilambwe

    Sudan Hansraj, Sunil D. Maharaj, and Brian Chilambwe. C onstant potentials in 6d einstein- gauss-bonnet theory. Phys. Rev. D , 100:124029, Dec 2019

  24. [32]

    A relation between distance and radial ve locity among extra-galactic nebulae

    Edwin Hubble. A relation between distance and radial ve locity among extra-galactic nebulae. Proceedings of the National Academy of Sciences , 15(3):168–173, 1929

  25. [33]

    Ibragimov

    N.K. Ibragimov. Elementary Lie group analysis and ordinary differential equa tions. Mathe- matical methods in practice. Wiley, 1999

  26. [34]

    Karmarkar

    K.R. Karmarkar. Proc. Ind. Acad. Sci. A , 27(56):56, 1948

  27. [35]

    Highe r dimensional generalization of the buchdahl-vaidya-tikekar model for a supercompact star

    Avas Khugaev, Naresh Dadhich, and Alfred Molina. Highe r dimensional generalization of the buchdahl-vaidya-tikekar model for a supercompact star. Phys. Rev. D , 94:064065, Sep 2016. 19

  28. [36]

    Lifshitz. Landau. The classical theory of fields , volume Volume 2. Butterworth Heinemann, 4 edition, 1994

  29. [37]

    Maharaj, Brian Chilambwe, and Sudan Hansraj

    Sunil D. Maharaj, Brian Chilambwe, and Sudan Hansraj. E xact barotropic distributions in einstein-gauss-bonnet gravity. Phys. Rev. D , 91:084049, Apr 2015

  30. [38]

    Misner, K.S

    C.W. Misner, K.S. Thorne, J.A. Wheeler, and D.I. Kaiser . Gravitation. Princeton University Press, 2017

  31. [39]

    Emergent un iverse in einstein-gauss-bonnet theory

    Sudeshna Mukerji and Subenoy Chakraborty. Emergent un iverse in einstein-gauss-bonnet theory. Int. J. Theor. Phys , 49(10):2446, 2010

  32. [40]

    Myers and Jonathan Z

    Robert C. Myers and Jonathan Z. Simon. Black-hole therm odynamics in lovelock gravity. Phys. Rev. D , 38:2434–2444, Oct 1988

  33. [41]

    A. V. Nikolaev and S. V. Chervon. The effect of universe inh omogeneities on cosmological distance measurements. Gravitation and Cosmology , 22(2):208–211, 2016

  34. [42]

    Effects of lovelock terms on the final fate of gravitational collapse: analysis in dimensionally continued gravity

    Masato Nozawa and Hideki Maeda. Effects of lovelock terms on the final fate of gravitational collapse: analysis in dimensionally continued gravity. Class. Quantum Grav. , 23(5):1779–1800, feb 2006

  35. [43]

    Pavluchenko and Alexey Toporensky

    Sergey A. Pavluchenko and Alexey Toporensky. Effects of s patial curvature and anisotropy on the asymptotic regimes in einstein–gauss–bonnet gravity. Eur. Phys. J. C , 78(5):373, 2018

  36. [44]

    Planck Collaboration, P. A. R. Ade, Aghanim, and et.al. Planck 2015 results - xiii. cosmological parameters. A&A, 594:A13, 2016

  37. [45]

    A. R. Prasanna. A note on an invariant of spherically sym metric space-times. Current Science Association, 38(19):455–456, 1969

  38. [46]

    Gra vitational collapse in generalized vaidya space-time for lovelock gravity theory

    Prabir Rudra, Ritabrata Biswas, and Ujjal Debnath. Gra vitational collapse in generalized vaidya space-time for lovelock gravity theory. Astrophys. Space Sci. , 335(2):505, 2011

  39. [47]

    Compact star model in einstein –gauss–bonnet gravity within the framework of finch skea space–time

    Iftikar Hossain Sardar. Compact star model in einstein –gauss–bonnet gravity within the framework of finch skea space–time. Can. J. Phys. , 97(1):30–36, 2019

  40. [48]

    Exact solutions of Einstein ’s field equations

    Hans Stephani, Dietrich Kramer, Malcolm MacCallum, Co rnelius Hoenselaers, and Eduard Herlt. Exact solutions of Einstein ’s field equations . Cambridge University Press, Cambridge, 2003

  41. [49]

    R.S. Tikekar. A suspected converse of a theorem regardi ng spherically symmetric space-times. Current Science, 20:461, 1970

  42. [50]

    J. M. Toledo and V. B. Bezerra. Black holes with quintess ence in pure lovelock gravity. Gen. 20 Relativ. Gravit., 51(3):41, Mar 2019

  43. [51]

    Cosmology

    Steven Weinberg. Cosmology. Oxford University Press, USA, oup edition, 2008

  44. [52]

    James T. Wheeler. Symmetric solutions to the gauss-bon net extended einstein equations. Nucl. Phys. B , 268(3):737 – 746, 1986

  45. [53]

    James T. Wheeler. Symmetric solutions to the maximally gauss-bonnet extended einstein equations. Nucl. Phys. B , 273(3):732 – 748, 1986

  46. [54]

    Wiltshire

    D.L. Wiltshire. Spherically symmetric solutions of ei nstein-maxwell theory with a gauss- bonnet term. Phys. Lett. B , 169(1):36 – 40, 1986

  47. [55]

    A comparative study between egb gravit y and gtr by modeling compact stars

    Matthew Wright. A comparative study between egb gravit y and gtr by modeling compact stars. Gen. Relativ. Gravit. , 48(7):93, 2016

  48. [56]

    St atic spherically symmetric star in gauss-bonnet gravity

    Zou De-Cheng Yue Rui-Hong Zhou Kang, Yang Zhan-Ying. St atic spherically symmetric star in gauss-bonnet gravity. Chin. Phys. B , 21(2):20401, 2012. Riemann tensor in N -dimensional spherical symmetric spacetime In this appendix our goal is to proof (6a)-(6b) which we made by g...

  49. [57]

    It is true for α = 3 g33 − g22 cos2 φ 1 sin2 φ 1 = g33 − g33 cos2 φ 1 = g33 sin2 φ 1 = g22. (68) 22

  50. [58]

    As a result we proofed (67)

    If it is true for α = n > 3 gnn − n−1∑ γ =2 gγγ cos2 φ γ −1 sin2 φ γ −1 = g22, (69) then for α = n + 1 it is gn+1n+1 − gnn cos2 φ n−1 sin2 φ n−1 − n−1∑ γ =2 gγγ cos2 φ γ −1 sin2 φ γ −1 = gn+1n+1 − gn+1n+1 cos2 φ n−1 − n−1∑ γ =2 gγγ cos2 φ γ −1 sin2 φ γ −1 = gnn − n−1∑ γ =2 gγγ...

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