Cosmological Dynamics in Quadratic f(R,G) Gravity with a Periodically Evolving Deceleration Parameter

Dhajendra Rabha; Rajshekhar Roy Baruah

doi:doi:10.11648/j.ijass.20261403.12

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Cosmological Dynamics in Quadratic f(R,G) Gravity with a Periodically Evolving Deceleration Parameter

Dhajendra Rabha

, Rajshekhar Roy Baruah^*

Published in International Journal of Astrophysics and Space Science (Volume 14, Issue 3)

Received: 19 August 2026 Accepted: 19 August 2026 Published: 21 September 2026

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Abstract

baselineskip=12pt The late-time accelerated expansion of the Universe remains one of the major challenges in modern cosmology, motivating the exploration of modified theories of gravity as alternatives to the standard ΛCDM framework. In this work, we investigate the cosmological evolution of a spatially flat Friedmann–Lemaitre–Robertson–Walker (FLRW) universe within the framework of f(R,G) gravity, where both the Ricci scalar R and the Gauss–Bonnet invariant G contribute to the gravitational dynamics. We consider quadratic corrections to the Ricci scalar and Gauss-Bonnet invariant, with (ξ) and (λ) denoting the corresponding coupling parameters. To obtain the cosmological solutions, the modified field equations are analyzed by adopting a periodically varying deceleration parameter through a suitable parametrization of the scale factor. The resulting cosmological model is examined in detail in terms of its expansion history, dynamical evolution, scalar field correspondence, and energy conditions. The model describes an initially singular Universe characterized by vanishing volume and divergent energy density, followed by a transition to an accelerated expansion phase. The evolution of the effective equation-of-state parameter indicates a quintessence-like behavior of the dark-energy sector during the relevant stages of cosmic evolution. Furthermore, the model gradually approaches the behavior of the standard ΛCDM cosmology at late times. The analysis of the energy conditions and cosmological parameters demonstrates that the proposed quadratic f(R,G) model provides a physically viable description of the observed late-time cosmic acceleration. These results indicate that the combined quadratic Ricci and Gauss–Bonnet corrections can provide an effective geometric mechanism for describing the accelerated expansion of the Universe without requiring a separate dark-energy component.

Published in	International Journal of Astrophysics and Space Science (Volume 14, Issue 3)
DOI	10.11648/j.ijass.20261403.12
Page(s)	53-68
Creative Commons	This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.
Copyright	Copyright © The Author(s), 2026. Published by Science Publishing Group

Keywords

f(R, G) Gravity, Quintessence, Dark Energy, Λ CDM Model

References

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Rabha, D., Baruah, R. R. (2026). Cosmological Dynamics in Quadratic f(R,G) Gravity with a Periodically Evolving Deceleration Parameter. International Journal of Astrophysics and Space Science, 14(3), 53-68. https://doi.org/10.11648/j.ijass.20261403.12

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Rabha, D.; Baruah, R. R. Cosmological Dynamics in Quadratic f(R,G) Gravity with a Periodically Evolving Deceleration Parameter. Int. J. Astrophys. Space Sci. 2026, 14(3), 53-68. doi: 10.11648/j.ijass.20261403.12

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Rabha D, Baruah RR. Cosmological Dynamics in Quadratic f(R,G) Gravity with a Periodically Evolving Deceleration Parameter. Int J Astrophys Space Sci. 2026;14(3):53-68. doi: 10.11648/j.ijass.20261403.12

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@article{10.11648/j.ijass.20261403.12,
  author = {Dhajendra Rabha and Rajshekhar Roy Baruah},
  title = {Cosmological Dynamics in Quadratic f(R,G) Gravity with a Periodically Evolving Deceleration Parameter},
  journal = {International Journal of Astrophysics and Space Science},
  volume = {14},
  number = {3},
  pages = {53-68},
  doi = {10.11648/j.ijass.20261403.12},
  url = {https://doi.org/10.11648/j.ijass.20261403.12},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ijass.20261403.12},
  abstract = {baselineskip=12pt The late-time accelerated expansion of the Universe remains one of the major challenges in modern cosmology, motivating the exploration of modified theories of gravity as alternatives to the standard ΛCDM framework. In this work, we investigate the cosmological evolution of a spatially flat Friedmann–Lemaitre–Robertson–Walker (FLRW) universe within the framework of f(R,G) gravity, where both the Ricci scalar R and the Gauss–Bonnet invariant G contribute to the gravitational dynamics. We consider quadratic corrections to the Ricci scalar and Gauss-Bonnet invariant, with (ξ) and (λ) denoting the corresponding coupling parameters. To obtain the cosmological solutions, the modified field equations are analyzed by adopting a periodically varying deceleration parameter through a suitable parametrization of the scale factor. The resulting cosmological model is examined in detail in terms of its expansion history, dynamical evolution, scalar field correspondence, and energy conditions. The model describes an initially singular Universe characterized by vanishing volume and divergent energy density, followed by a transition to an accelerated expansion phase. The evolution of the effective equation-of-state parameter indicates a quintessence-like behavior of the dark-energy sector during the relevant stages of cosmic evolution. Furthermore, the model gradually approaches the behavior of the standard ΛCDM cosmology at late times. The analysis of the energy conditions and cosmological parameters demonstrates that the proposed quadratic f(R,G) model provides a physically viable description of the observed late-time cosmic acceleration. These results indicate that the combined quadratic Ricci and Gauss–Bonnet corrections can provide an effective geometric mechanism for describing the accelerated expansion of the Universe without requiring a separate dark-energy component.},
 year = {2026}
}

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TY  - JOUR
T1  - Cosmological Dynamics in Quadratic f(R,G) Gravity with a Periodically Evolving Deceleration Parameter
AU  - Dhajendra Rabha
AU  - Rajshekhar Roy Baruah
Y1  - 2026/09/21
PY  - 2026
N1  - https://doi.org/10.11648/j.ijass.20261403.12
DO  - 10.11648/j.ijass.20261403.12
T2  - International Journal of Astrophysics and Space Science
JF  - International Journal of Astrophysics and Space Science
JO  - International Journal of Astrophysics and Space Science
SP  - 53
EP  - 68
PB  - Science Publishing Group
SN  - 2376-7022
UR  - https://doi.org/10.11648/j.ijass.20261403.12
AB  - baselineskip=12pt The late-time accelerated expansion of the Universe remains one of the major challenges in modern cosmology, motivating the exploration of modified theories of gravity as alternatives to the standard ΛCDM framework. In this work, we investigate the cosmological evolution of a spatially flat Friedmann–Lemaitre–Robertson–Walker (FLRW) universe within the framework of f(R,G) gravity, where both the Ricci scalar R and the Gauss–Bonnet invariant G contribute to the gravitational dynamics. We consider quadratic corrections to the Ricci scalar and Gauss-Bonnet invariant, with (ξ) and (λ) denoting the corresponding coupling parameters. To obtain the cosmological solutions, the modified field equations are analyzed by adopting a periodically varying deceleration parameter through a suitable parametrization of the scale factor. The resulting cosmological model is examined in detail in terms of its expansion history, dynamical evolution, scalar field correspondence, and energy conditions. The model describes an initially singular Universe characterized by vanishing volume and divergent energy density, followed by a transition to an accelerated expansion phase. The evolution of the effective equation-of-state parameter indicates a quintessence-like behavior of the dark-energy sector during the relevant stages of cosmic evolution. Furthermore, the model gradually approaches the behavior of the standard ΛCDM cosmology at late times. The analysis of the energy conditions and cosmological parameters demonstrates that the proposed quadratic f(R,G) model provides a physically viable description of the observed late-time cosmic acceleration. These results indicate that the combined quadratic Ricci and Gauss–Bonnet corrections can provide an effective geometric mechanism for describing the accelerated expansion of the Universe without requiring a separate dark-energy component.
VL  - 14
IS  - 3
ER  -

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Dhajendra Rabha

Department of Mathematical Sciences, Bodoland University, Kokrajhar, India

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http://orcid.org/0000-0001-9641-6307
Rajshekhar Roy Baruah

Department of Mathematical Sciences, Bodoland University, Kokrajhar, India

Contact Email

http://orcid.org/0000-0002-5961-9540

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Rabha, D., Baruah, R. R. (2026). Cosmological Dynamics in Quadratic f(R,G) Gravity with a Periodically Evolving Deceleration Parameter. International Journal of Astrophysics and Space Science, 14(3), 53-68. https://doi.org/10.11648/j.ijass.20261403.12

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ACS Style

Rabha, D.; Baruah, R. R. Cosmological Dynamics in Quadratic f(R,G) Gravity with a Periodically Evolving Deceleration Parameter. Int. J. Astrophys. Space Sci. 2026, 14(3), 53-68. doi: 10.11648/j.ijass.20261403.12

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AMA Style

Rabha D, Baruah RR. Cosmological Dynamics in Quadratic f(R,G) Gravity with a Periodically Evolving Deceleration Parameter. Int J Astrophys Space Sci. 2026;14(3):53-68. doi: 10.11648/j.ijass.20261403.12

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@article{10.11648/j.ijass.20261403.12,
  author = {Dhajendra Rabha and Rajshekhar Roy Baruah},
  title = {Cosmological Dynamics in Quadratic f(R,G) Gravity with a Periodically Evolving Deceleration Parameter},
  journal = {International Journal of Astrophysics and Space Science},
  volume = {14},
  number = {3},
  pages = {53-68},
  doi = {10.11648/j.ijass.20261403.12},
  url = {https://doi.org/10.11648/j.ijass.20261403.12},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ijass.20261403.12},
  abstract = {baselineskip=12pt The late-time accelerated expansion of the Universe remains one of the major challenges in modern cosmology, motivating the exploration of modified theories of gravity as alternatives to the standard ΛCDM framework. In this work, we investigate the cosmological evolution of a spatially flat Friedmann–Lemaitre–Robertson–Walker (FLRW) universe within the framework of f(R,G) gravity, where both the Ricci scalar R and the Gauss–Bonnet invariant G contribute to the gravitational dynamics. We consider quadratic corrections to the Ricci scalar and Gauss-Bonnet invariant, with (ξ) and (λ) denoting the corresponding coupling parameters. To obtain the cosmological solutions, the modified field equations are analyzed by adopting a periodically varying deceleration parameter through a suitable parametrization of the scale factor. The resulting cosmological model is examined in detail in terms of its expansion history, dynamical evolution, scalar field correspondence, and energy conditions. The model describes an initially singular Universe characterized by vanishing volume and divergent energy density, followed by a transition to an accelerated expansion phase. The evolution of the effective equation-of-state parameter indicates a quintessence-like behavior of the dark-energy sector during the relevant stages of cosmic evolution. Furthermore, the model gradually approaches the behavior of the standard ΛCDM cosmology at late times. The analysis of the energy conditions and cosmological parameters demonstrates that the proposed quadratic f(R,G) model provides a physically viable description of the observed late-time cosmic acceleration. These results indicate that the combined quadratic Ricci and Gauss–Bonnet corrections can provide an effective geometric mechanism for describing the accelerated expansion of the Universe without requiring a separate dark-energy component.},
 year = {2026}
}

Copy | Download

TY  - JOUR
T1  - Cosmological Dynamics in Quadratic f(R,G) Gravity with a Periodically Evolving Deceleration Parameter
AU  - Dhajendra Rabha
AU  - Rajshekhar Roy Baruah
Y1  - 2026/09/21
PY  - 2026
N1  - https://doi.org/10.11648/j.ijass.20261403.12
DO  - 10.11648/j.ijass.20261403.12
T2  - International Journal of Astrophysics and Space Science
JF  - International Journal of Astrophysics and Space Science
JO  - International Journal of Astrophysics and Space Science
SP  - 53
EP  - 68
PB  - Science Publishing Group
SN  - 2376-7022
UR  - https://doi.org/10.11648/j.ijass.20261403.12
AB  - baselineskip=12pt The late-time accelerated expansion of the Universe remains one of the major challenges in modern cosmology, motivating the exploration of modified theories of gravity as alternatives to the standard ΛCDM framework. In this work, we investigate the cosmological evolution of a spatially flat Friedmann–Lemaitre–Robertson–Walker (FLRW) universe within the framework of f(R,G) gravity, where both the Ricci scalar R and the Gauss–Bonnet invariant G contribute to the gravitational dynamics. We consider quadratic corrections to the Ricci scalar and Gauss-Bonnet invariant, with (ξ) and (λ) denoting the corresponding coupling parameters. To obtain the cosmological solutions, the modified field equations are analyzed by adopting a periodically varying deceleration parameter through a suitable parametrization of the scale factor. The resulting cosmological model is examined in detail in terms of its expansion history, dynamical evolution, scalar field correspondence, and energy conditions. The model describes an initially singular Universe characterized by vanishing volume and divergent energy density, followed by a transition to an accelerated expansion phase. The evolution of the effective equation-of-state parameter indicates a quintessence-like behavior of the dark-energy sector during the relevant stages of cosmic evolution. Furthermore, the model gradually approaches the behavior of the standard ΛCDM cosmology at late times. The analysis of the energy conditions and cosmological parameters demonstrates that the proposed quadratic f(R,G) model provides a physically viable description of the observed late-time cosmic acceleration. These results indicate that the combined quadratic Ricci and Gauss–Bonnet corrections can provide an effective geometric mechanism for describing the accelerated expansion of the Universe without requiring a separate dark-energy component.
VL  - 14
IS  - 3
ER  -

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