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In this study, we investigate the role of bulk viscosity in $f(Q,T)$ gravity in explaining late-time cosmic acceleration. This model, an extension of symmetric teleparallel gravity, introduces viscosity into cosmic matter dynamics for a…

Cosmology and Nongalactic Astrophysics · Physics 2024-05-14 M. Koussour , Abdelghani Errehymy , O. Donmez , K. Myrzakulov , M. A. Khan , B. Çil , E. Güdekli

We reconstruct the effective Equation of State (EoS) within the framework of General Relativity (GR) theory in a homogeneous and isotropic FLRW Universe, which is assumed to be composed of matter and Dark Energy (DE). Our analysis employs a…

General Relativity and Quantum Cosmology · Physics 2023-09-29 N. Myrzakulov , M. Koussour , Alnadhief H. A. Alfedeel , E. I. Hassan

In this work, we present a method for numerically solving the Friedmann equations of modified $f(\mathcal{G})$ gravity in the presence of pressureless matter. This method enables us to predict the redshift behaviour of the Hubble expansion…

General Relativity and Quantum Cosmology · Physics 2024-11-08 Santosh V. Lohakare , Soumyadip Niyogi , B. Mishra

We are experiencing a golden age of experimental cosmology, with exact and accurate observations being used to constrain various gravitational theories like never before. Alongside these advancements, energy conditions play a crucial…

Cosmology and Nongalactic Astrophysics · Physics 2025-04-08 Y. Myrzakulov , O. Donmez , M. Koussour , S. Muminov , D. Ostemir , J. Rayimbaev

The current transit universe model is a precise solution to the equations of a new type of gravity theory called metric-affine $f(R,T,Q,T_m)$ gravity proposed in [Herko et al. \textit{Phys. Dark Univ.} \textbf{34} (2021) 100886]. This…

General Relativity and Quantum Cosmology · Physics 2026-02-19 Dinesh Chandra Maurya , Harjit Kumar

This thesis explores the cosmological implications of modified gravity, focusing on nonmetricity-based $f(Q)$ gravity as an alternative to the $\Lambda$CDM model in explaining cosmic acceleration. Chapter I lays the theoretical groundwork…

General Relativity and Quantum Cosmology · Physics 2025-04-15 Gaurav N. Gadbail

In the present article, we developed a dynamical system in the context of modified $f(R,G,T)$ gravity, where $R$, $G$ and $T$ are Ricci scalar, Gauss-Bonnet term and energy-momentum tensor respectively. Development of the dynamical system…

General Relativity and Quantum Cosmology · Physics 2025-05-30 Elangbam Chingkheinganba Meetei , S. Surendra Singh

Recently, Tsallis, R\'{e}nyi and Sharma-Mitall and entropies have widely been used to study the gravitational and cosmological setups. We consider a flat FRW universe with linear interaction between dark energy and dark matter. We discuss…

General Physics · Physics 2019-01-08 M. Younas , Abdul Jawad , Saba Qummer , H. Moradpour , Shamaila Rani

This paper is devoted to examining cosmological bouncing scenarios in the framework of the recently proposed symmetric teleparallel gravity (or $f(Q)$ gravity), where the non-metricity scalar $Q$ represents the gravitational interaction. We…

Cosmology and Nongalactic Astrophysics · Physics 2024-09-17 M. Koussour , N. Myrzakulov

We investigate alternative candidates to dark energy that can explain the current state of the universe in the framework of the generalized teleparallel theory of gravity $f(T)$ where $T$ denotes the torsion scalar. To achieve this, we…

General Physics · Physics 2020-08-26 A. E. Godonou , Ines G. Salako , M. J. S. Houndjo , Etienne Baffou , Joel Tossa

In view of late-time cosmic acceleration, a dark energy cosmological model is revisited wherein Einstein's cosmological constant is considered as a candidate of dark energy. Exact solution of Einstein field equations (EFEs) is derived in a…

General Relativity and Quantum Cosmology · Physics 2019-11-22 S. K. J. Pacif , Md Salahuddin Khan , L. K. Paikroy , Shalini Singh

The expansion of the Universe in $f(R,T)$ gravity is studied. We consider functions of the form $f(R,T)=R+\lambda T^\epsilon$ where $\epsilon<1$. We find that for all models with $\epsilon<0$, the Universe transitions to exponential growth…

General Relativity and Quantum Cosmology · Physics 2026-03-26 Vincent R. Siggia , Eric D. Carlson , P. Lee Pryor

Inspired by String T-duality and taking into account the zero-point length correction, $l_0$, to the gravitational potential, we construct modified Friedmann equations by applying the first law of thermodynamics on the apparent horizon of…

General Relativity and Quantum Cosmology · Physics 2024-12-17 Giuseppe Gaetano Luciano , Ahmad Sheykhi

In the last dozen years a wide and variegated mass of observational data revealed that the universe is now expanding at an accelerated rate. In the absence of a well-based theory to interpret the observations, cosmography provides…

Cosmology and Nongalactic Astrophysics · Physics 2015-09-30 Ester Piedipalumbo , Enrica Della Moglie , Roberto Cianci

The reconstruction of f(R)-gravity is showed by using an auxiliary scalar field in the context of cosmological evolution, this development provide a way of reconstruct the form of the function f (R) for a given evolution of the Hubble…

High Energy Physics - Theory · Physics 2009-07-22 Diego Sáez-Gómez

In this work, we explore the cosmological dynamics of a modified gravity framework based on the function $f(Q,B)=\delta Q^{2}+\beta B$, where $Q$ denotes the nonmetricity scalar and $B$ is the boundary term that relates $Q$ to the Ricci…

General Relativity and Quantum Cosmology · Physics 2025-07-22 Amit Samaddar , S. Surendra Singh

One of the central challenges in modern cosmology is understanding the nature of dark energy and its evolution throughout the history of the Universe. Dark energy is commonly modeled as a perfect fluid with a time-varying equation-of-state…

Cosmology and Nongalactic Astrophysics · Physics 2025-02-26 Samsuzzaman Afroz , Suvodip Mukherjee

In this work, we investigate the cosmological dynamics of an anisotropic Universe within the framework of $f(R,T)$ gravity by incorporating pressureless dark matter and the dark energy models. The analysis is carried out in a Bianchi type-I…

General Relativity and Quantum Cosmology · Physics 2026-05-13 S. H. Shekh , N. Myrzakulov , Anirudh Pradhan , M. Zeyauddin

The $f(R, T)$ theory of gravity extends general relativity (GR) by allowing the gravitational Lagrangian to depend on both the Ricci scalar $R$ and the trace of the energy-momentum tensor $T$. The resulting matter-geometry coupling…

General Relativity and Quantum Cosmology · Physics 2026-02-16 Serkan Doruk Hazinedar , Yaghoub Heydarzade , Shahram Jalalzadeh

This thesis investigates the characteristics of modified teleparallel gravity models that incorporate a scalar field and a trace of the energy-momentum tensor, with particular attention to their cosmological effects, especially regarding…

General Relativity and Quantum Cosmology · Physics 2025-10-06 L K Duchaniya