arXiv subjects

Salih Kibaroğlu

Publications and source records attributed to Salih Kibaroğlu.

At least 19 recordsLinked to original sources

arXiv2026

Exact vacuum FLRW solutions in $q$-deformed Brans-Dicke cosmology

We study a $q$-deformed extension of Brans-Dicke gravity in a spatially flat Friedmann-Lemaître-Robertson-Walker space-time. The deformation enters through a coupling function that modifies the effective gravitational strength and leads to generalized Friedmann equations. In the matter-free sector, we obtain exact analytic solutions for the scale factor and the Brans-Dicke scalar field, and recast the scalar contribution as an effective fluid. We show that the corresponding equation-of-state parameter and the deceleration parameter are constants and depend only on the Brans-Dicke coupling $ω$ and the deformation function, allowing the scalar sector to mimic radiation-, matter-, or dark-energy-like behavior for a restricted region of parameter space.

gr-qc↗

arXiv2026

Born-Infeld-f(R) black holes

We explore black hole solutions in the context of Born-Infeld-f(R) gravity, a modified gravitational framework that extends both Born-Infeld and f(R) theories. By adopting a static, spherically symmetric spacetime ansatz, we derive an exact black hole solution and investigate its geometrical structure. We proceed to analyze the thermodynamic properties of the solution, including the Hawking temperature, entropy, and specific heat, with particular emphasis on their dependence on the model parameters. Our results reveal novel thermodynamic behavior that deviates significantly from the standard predictions of general relativity. A comparative study with the Schwarzschild-AdS black holes is also presented, showing how Born-Infeld-f(R) corrections alter black hole thermodynamics.

gr-qc↗

arXiv2026

Torsion-Induced Modification to Friedmann Equations in $AdSL_{4}$ Gauged Gravity

We study the solution of the gravitational field equations in $AdSL_{4}$-gauged gravity, a gauge-theoretic extension of general relativity based on the $AdSL_{4}$ algebra. In this formulation, the antisymmetric gauge field $B^{ab}$, associated with additional $AdSL_{4}$ tensorial generators, induces space-time torsion via the relation $K^{ab}=μB^{ab}$, where $K^{ab}$ denotes the contorsion 1-form. The presence of torsion modifies both the spin connection and curvature, leading to an extended set of Einstein-Cartan field equations. Focusing on spatially homogeneous and isotropic cosmological backgrounds, we derive the modified Friedmann equations which explicitly incorporate the torsional contribution. The resulting acceleration equation admits de Sitter-like solutions in which cosmic acceleration originates purely from the gauge-theoretic structure of enlarged four-dimensional space-time symmetries. Within this formulation, the dynamical components of the gauge field $B^{ab}$ emerge naturally as a source of the effective cosmological constants, without the introduction of exotic matter sources. Furthermore, our analysis shows that the torsion-driven cosmological phase in $AdSL_{4}$-gauged gravity can reproduce an effective equation-of-state parameter $ω_{B}=-1/3$, establishing a connection between space-time torsion and cosmic-string-like dynamics.

hep-th↗

arXiv2025

Generalized Brans-Dicke theory from Verlinde's entropic gravity

In this work, we develop a q-deformed scalar-tensor theory of gravitation by combining Verlinde's entropic gravity paradigm with statistical deformation effects. The resulting model modifies the Brans-Dicke framework through a deformation function, treated as a constant rescaling factor for the effective gravitational coupling. We derive the corresponding q-deformed field equations and analyze their theoretical consistency including the recovery of standard gravitational models in specific limits. While the present formulation preserves key symmetries and provides a generalized description of gravitational dynamics, it does not yield a significant deviation from Brans-Dicke theory. The study concludes with prospects for future research, including the exploration of cosmological solutions arising from the q-deformed field equations.

gr-qc↗

arXiv2025

Anisotropic cosmology in $q$-deformed entropic gravity

In this work, we examine the implications of $q$-deformed theory on anisotropic Bianchi type-I cosmological model within the framework of Verlinde's entropic gravity. The $q$-deformed theory, rooted in quantum group structures, provides a natural generalization of classical particle dynamics and offers a useful framework for exploring deviations in standard cosmological models. By incorporating the principles of entropic gravity, which conceptualize gravity as an emergent entropic force, we derive the dynamical equations governing the Bianchi type-I anisotropic model influenced by $q$-deformation. Finally, we analyze the axisymmetric solution of Bianchi type-I model and these findings highlight the potential impact of $q$-deformation on the dynamics of the early universe and its subsequent evolution.

gr-qc↗

arXiv2024

Anisotropic Born-Infeld-f(R) Cosmologies

In this paper, we investigate anisotropic cosmological solutions within the framework of Born-Infeld-f(R) gravity, a modification of general relativity that incorporates higher-order curvature invariants. Specifically, we focus on the analysis of Bianchi type-I solutions, which provide a valuable framework for studying the evolution of spatial anisotropies in cosmology. By introducing a reconstruction scheme for this model, we explore the behavior of these solutions, analyze various cosmic evolution scenarios, including Starobinsky inflation, de Sitter-like expansion, power-law dynamics, and Big Rip-like evolution. Additionally, we examine the exponential and power-law behavior of the auxiliary metric function to illustrate its impact on the dynamics of cosmic evolution. Our analysis elucidates how the modifications introduced by Born-Infeld-f(R) gravity influence anisotropic dynamics, offering new perspectives on the late-time behavior of the universe and potential future singularities.

gr-qc↗

arXiv2024

Modified Friedmann Equations from Maxwell-Weyl Gauge Theory

This study investigates the possibility of a homogeneous and isotropic cosmological solution within the context of the Maxwell-Weyl gauge theory of gravity. To achieve this, we utilize the Einstein-Yang-Mills theory as an analogy and represent the Maxwell gauge field in terms of two time-dependent scalar fields. We derive the modified Friedmann equations, integrating the contributions from the Maxwell gauge fields and an effective cosmological constant that depends on the Dirac scalar field. Our analysis reveals how these modifications influence various cosmological scenarios, including power-law evolution, de Sitter-like expansion, inflationary phases, non-singular bounce cosmologies, and cyclic cosmologies.

gr-qc↗

arXiv2024

Cosmology of unimodular Born-Infeld-$f(R)$ gravity

We propose a novel modified gravity: unimodular generalization of the Born-Infeld-$f(R)$ gravity within the framework of cosmology. After formulating the action corresponding to the generalized Born-Infeld-$f(R)$ gravity, we present a reconstruction scheme of this unimodular extension to achieve various cosmological eras of the universe. Interestingly, the unimodular generalization of Born-Infeld-$f(R)$ gravity proves to be suitable for inflation (de-Sitter and quasi de-Sitter) along with power law cosmology which actually includes from reheating to the Standard Big-Bang cosmology. Apart from the inflation, such generalized Born-Infeld-$f(R)$ theory is also capable to trigger non-singular bouncing cosmology for suitable forms of the unimodular Lagrange multiplier, which are exotic for the standard Einstein-Hilbert gravity and cannot be realized in that case. The possible consequences are discussed.

gr-qc↗

arXiv2023

Cosmological application of the Maxwell gravity

In this study, we consider a cosmological model for the Maxwell gravity which is constructed by gauging the semi-simple extended Poincaré algebra. Inspired by the Einstein-Yang-Mills theory, we describe the Maxwell gauge field in terms of two additional time-dependent scalar fields. Within the context of a homogeneous and isotropic Friedmann-Lemaître-Robertson-Walker universe, we derive the Friedmann equations together with new contributions. Additionally, we find the exact expressions for the additional scalar fields, considering the exponential evolution of the scale factor. Moreover, we investigate the gauge theory of gravity based on the Maxwell algebra and demonstrate that this model leads to the (anti) de Sitter universe as well as a non-accelerated universe model.

hep-th↗

arXiv2023

Gauging the Maxwell extended $\mathcal{GL}\left(n,\mathbb{R}\right)$ and $\mathcal{SL}\left(n+1,\mathbb{R}\right)$ algebras

We consider the extension of the general-linear and special-linear algebras by employing the Maxwell symmetry in $D$ space-time dimensions. We show how various Maxwell extensions of the ordinary space-time algebras can be obtained by a suitable contraction of generalized algebras. The extended Lie algebras could be useful in the construction of generalized gravity theories and the objects that couple to them. We also consider the gravitational dynamics of these algebras in the framework of the gauge theories of gravity. By adopting the symmetry-breaking mechanism of the Stelle-West model, we present some modified gravity models that contain the generalized cosmological constant term in four dimensions.

hep-th↗

arXiv2023

Born-Infeld-$f(R)$ gravity with de Sitter solutions

In this study, we consider the Born--Infeld-$f(R)$ gravity in which the $f(R)$ term enters directly into the square root in the Palatini formulation. We shortly analyzed this model for an explicit $f(R)$ function which includes positive and negative powers of the curvature scalar. We also show that both the ordinary Born--Infeld-$f(R)$ and this modification reduce to the same gravitational action form under the conformal approach. Then we consider the existence of a maximally symmetric vacuum solution for the gravitational field equations and find the de Sitter solution for this modified model.

gr-qc↗

arXiv2023

Maxwell extension of $f(R)$ gravity

Inspired by the Maxwell symmetry generalization of general relativity (Maxwell gravity), we have constructed the Maxwell extension of $f(R)$ gravity. We found that the semi-simple extension of the Poincare symmetry allows us to introduce geometrically a cosmological constant term in four-dimensional $f(R)$ gravity. This symmetry also allows the introduction of a non-vanishing torsion to the Maxwell $f(R)$ theory. It is found that the antisymmetric gauge field $B^{ab}$ associated with Maxwell extension is considered as a source of the torsion. It is also found that the gravitational equation of motion acquires a new term in the form of an energy-momentum tensor for the background field. The importance of these new equations is briefly discussed.

hep-th↗

arXiv2022

Cosmological implications of Born-Infeld-$f(R)$ gravity

A modified Born-Infeld gravitation theory with a $f\left(R\right)$ function being added to the determinant action is analyzed from a cosmological viewpoint. The corresponding accelerating dynamics are studied in a simplified conformal approach without matter. Three different structures for the auxiliary metric function are analyzed, with the aim to establish a deeper understanding of the role of this function in cosmology. After performing the analysis, it is seen that, by modifying the auxiliary metric function, a Big Rip singularity or either a Little Rip dark energy model may arise.

gr-qc↗

arXiv2022

GUP-corrected $Λ$CDM cosmology

In this study, we investigate the effect of the generalized uncertainty principle on the $Λ$CDM cosmological model. Using quantum corrected Unruh effect and Verlinde's entropic gravity idea, we find Planck-scale corrected Friedmann equations with a cosmological constant. These results modify the $Λ$CDM cosmology.

gr-qc↗

arXiv2021

Maxwell-Modified Metric Affine Gravity

We present a gauge formulation of the special affine algebra extended to include an antisymmetric tensorial generator belonging to the tensor representation of the special linear group. We then obtain a Maxwell modified metric affine gravity action with a cosmological constant term. We find the field equations of the theory and show that the theory reduces to an Einstein-like equation for metric affine gravity with the source added to the gravity equations with cosmological constant μcontains linear contributions from the new gauge fields. The reduction of the Maxwell metric affine gravity to Riemann-Cartan one is discussed and the shear curvature tensor corresponding to the symmetric part of the special linear connection is identified with the dark energy. Furthermore, the new gauge fields interpreted as geometrical inflaton vector fields which drive accelerated expansion.

hep-th↗

arXiv2021

Gauge theory of the Maxwell and semi-simple extended (anti) de Sitter algebra

In this paper, a semi-simple and Maxwell extension of the (anti) de Sitter algebra is constructed. Then, a gauge-invariant model has been presented by gauging the Maxwell semi-simple extension of the (anti) de Sitter algebra. We firstly construct a Stelle-West like model action for five-dimensional space-time in which the effects of spontaneous symmetry breaking have been taken into account. In doing so, we get an extended version of Einstein's field equations. Next, we decompose the five-dimensional extended Lie algebra and establish a MacDowell-Mansouri like action that contains the Einstein-Hilbert term, the cosmological term as well as new terms coming from Maxwell extension in four-dimensional space-time where the torsion-free condition is assumed. Finally, we have shown that both models are equivalent for an appropriately chosen gauge condition.

hep-th↗

arXiv2020

Generalized cosmological constant from gauging Maxwell-conformal algebra

The Maxwell extension of the conformal algebra is presented. With the help of gauging the Maxwell-conformal group, a conformally invariant theory of gravity is constructed. In contrast to the conventional conformally invariant actions, our gravitational action contains the Einstein-Hilbert term without introducing any additional (compensator) scalar field to satisfy the local scale invariance. This is achieved by using the curvatures of the algebra. In a special condition, we show that the resulting action is reduced to the Brans-Dicke like theory of gravity. We subsequently find the generalized Einstein field equation together with a coordinate dependent cosmological term and additional contributions.

hep-th↗

arXiv2019

$D=4$ supergravity from the Maxwell-Weyl superalgebra

Abstract We present the construction of the first-order $D=4$, $\mathcal{N}=1$ supergravity action by gauging the Maxwell-Weyl superalgebra. The four-form lagrangian is constructed by using the curvatures of the algebra and the local scale invariance of the action is achieved through the introduction of a compensating scalar field. Finally, we find the generalized Einstein equation with a coordinate dependent cosmological term.

hep-th↗