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The actual accelerated expansion of the universe continues being a mystery in physics. Some models had been proposed for this explanations, among them the dark energy, which however has problems of experimental character as well as…

General Relativity and Quantum Cosmology · Physics 2012-11-13 Alejandro Guarnizo

We investigate a spatially flat FLRW cosmological model in the framework of modified gravity described by the function \( f(R, L_m) = \alpha R + L_m^\beta + \gamma \), where \( L_m \) is the matter Lagrangian density. The modified Friedmann…

General Relativity and Quantum Cosmology · Physics 2026-02-05 G. K. Goswami , Anirudh Pradhan , Syamala Krishnannair

The theoretical and observational consequences of thermodynamics of open systems, which allow particle creation are investigated in modified $f(R,T)$ ($R$ is the Ricci scalar and $T$ is the trace of energy-momentum tensor) theory of gravity…

General Relativity and Quantum Cosmology · Physics 2014-08-26 C. P. Singh , Vijay Singh

Several models of $f(R)$ gravity have been proposed in order to address the dark side problem in cosmology. However, these models should be constrained also at ultraviolet scales in order to achieve some correct fundamental interpretation.…

General Relativity and Quantum Cosmology · Physics 2016-03-23 S. Capozziello , O. Luongo , M. Paolella

We provide insight about the full form of the equations for matter density perturbations and the scalar Bardeen metric potentials in general $f(R)$ theories of gravity. When considering viable modifications to the standard $\Lambda$CDM…

General Relativity and Quantum Cosmology · Physics 2026-01-21 Miguel Barroso Varela , Álvaro de la Cruz-Dombriz

The evolution of linear cosmological perturbations in modified theories of gravity is investigated assuming the Palatini formalism. It has been discussed about the stability problem in this model based on the equivalence between f(R)…

General Relativity and Quantum Cosmology · Physics 2008-06-18 Seokcheon Lee

We have probed a cosmological model in $f(R)$-gravity, which is a cubic equation in scalar curvature $R$. The terms arise due to nonlinear $f(R)$ function are treated as energy due to curvature inspired geometry. As a result, we find…

General Relativity and Quantum Cosmology · Physics 2023-05-03 G. K. Goswami , Rita Rani , Harshna Balhara , J. K. Singh

We present the method of describing an evolution in quantum cosmology in the framework of the reduced phase space quantization of loop cosmology. We apply our method to the flat Friedman-Robertson-Walker model coupled to a massless scalar…

General Relativity and Quantum Cosmology · Physics 2012-03-06 Jakub Mielczarek , Wlodzimierz Piechocki

The exact renormalization group flow equations for gravity lead to quantum corrections of Newton's constant and cosmological constant. Using this we investigate the Bianchi-I cosmological model at late times. In particular, we obtain the…

General Relativity and Quantum Cosmology · Physics 2022-08-11 Sunandan Gangopadhyay , Rituparna Mandal , Amitabha Lahiri

We investigate cosmological dynamics based on $f(R)$ gravity in the Palatini formulation. In this study we use the dynamical system methods. We show that the evolution of the Friedmann equation reduces to the form of the piece-wise smooth…

General Relativity and Quantum Cosmology · Physics 2018-05-30 Marek Szydlowski , Aleksander Stachowski

We consider the evolution of a flat Friedmann-Roberstson-Walker Universe in a higher derivative theories, including $\alpha R^{2}$ terms to the Einstein-Hilbert action in the presence of a variable gravitational and cosmological constants.…

General Relativity and Quantum Cosmology · Physics 2014-11-17 P. S. Debnath , B. C. Paul

In this article, we examine the dynamical evolution of flat FRW cosmological model in $f(R, L_m)$ gravity theory. We consider the general form of $f(R, L_m)$ defined as $f(R, L_m) = \Lambda + \frac{\alpha}{2} R + \beta L_m^n$, where…

General Relativity and Quantum Cosmology · Physics 2025-02-14 Aman Shukla , Rakesh Raushan , Raghavendra Chaubey

A four-dimensional timelike brane is considered as the boundary of the $SAdS_{5}$ bulk background. Exploiting the CFT/FRW-cosmology relation, we derive the self-gravitational corrections to the first Friedmann-like equation which is the…

High Energy Physics - Theory · Physics 2009-11-10 M. R. Setare

In this work we study classical bouncing solutions in the context of $f({\sf R},{\sf T})={\sf R}+h({\sf T})$ gravity in a flat {\sf FLRW} background using a perfect fluid as the only matter content. Our investigation is based on introducing…

General Relativity and Quantum Cosmology · Physics 2018-06-05 Hamid Shabani , Amir Hadi Ziaie

The modified field equations are written in logarithmic and power law versions of entropy corrected models in Einstein's gravity in the background of FRW universe. In one section, a brief review of the Ho$\check{\text r}$ava-Lifshitz…

General Relativity and Quantum Cosmology · Physics 2019-09-02 Tanwi Bandyopadhyay , Ujjal Debnath

An alternative to the Big Bang cosmologies is obtained by the Big Bounce cosmologies. In this paper, we study a bounce cosmology with a Type IV singularity occurring at the bouncing point, in the context of $F(R)$ modified gravity. We…

General Relativity and Quantum Cosmology · Physics 2017-01-17 S. D. Odintsov , V. K. Oikonomou

Horava and Melby-Thompson recently proposed a new version of the Horava-Lifshitz theory of gravity, in which the spin-0 graviton is eliminated by introducing a Newtonian pre-potential $\phi$ and a local U(1) gauge field $A$. In this paper,…

High Energy Physics - Theory · Physics 2011-02-23 Anzhong Wang , Yumei Wu

Modified gravity models are subject to a number of consistency requirements which restrict the form that the function $F(R)$ can take. We study a particular class of $F(R)$ functions which satisfy various constraints that have been found in…

Astrophysics · Physics 2010-04-06 Stephen A. Appleby , Richard A. Battye

We present a bounce universe in modified $f(Q,C)$ gravity considering linear as well as exponential form of gravity. Bounce cosmological models are introduced to remove the singularity problem of the early universe. A new quadratic boundary…

General Relativity and Quantum Cosmology · Physics 2025-08-07 Bhaswati Mandal , B. C. Paul

In recent few years, the Gauss-Bonnet $f(\mathcal{G},\mathrm{\textit{T}})$ theory of gravity has fascinated considerable researchers owing to its coupling of trace of the stress-energy tensor $T$ with the Gauss-Bonnet term $\mathcal{G}$. In…

General Relativity and Quantum Cosmology · Physics 2023-04-14 Mushtaq Ahmad , M. Farasat Shamir , G. Mustafa
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