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We discussed the dynamics of cosmological models in which the cosmological constant term is a time dependent function through the scale factor $a(t)$, Hubble function $H(t)$, Ricci scalar $R(t)$ and scalar field $\phi(t)$. We considered…

Cosmology and Nongalactic Astrophysics · Physics 2017-09-29 Aleksander Stachowski , Marek Szydlowski

Two parameters scale factor leading to bouncing cosmology is considered. We show that at some model parameters we obtain the deceleration parameter $q_0\approx -0.535$ at the current epoch which is in agreement with the Planck data. The…

General Physics · Physics 2026-05-18 S. I. Kruglov

We study the late-time cosmology in $f(R, G)=R+\alpha R^{2}+\beta e^{\gamma G}$, using a logarithmic parametrization of the deceleration parameter $q(z)=q_{0}+q_{1}sin[log(1+z)]$. The Hubble parameter $H(z)$ is reconstructed and model…

General Relativity and Quantum Cosmology · Physics 2025-06-10 Amit Samaddar , S. Surendra Singh

In this article, we study the expanding nature of universe in the contest of $f(R,L_m)$ gravity theory, here $ R $ represents the Ricci scalar and $ L_m $ is the matter Lagrangian density. With a specific form of $ f(R,L_m) $, we obtain the…

General Relativity and Quantum Cosmology · Physics 2023-06-28 J. K. Singh , Shaily , Ratbay Myrzakulov , Harshna Balhara

In the last few decades, extensions of General Relativity have reached always more attention especially in view of possible breakdowns of the standard $\Lambda$CDM paradigm at intermediate and high redshift regimes. If General Relativity…

General Relativity and Quantum Cosmology · Physics 2020-03-19 Marco Calzà , Alessandro Casalino , Orlando Luongo , Lorenzo Sebastiani

A family of cosmological solutions with $(n+1)$ Ricci-flat spaces in the theory with several scalar fields and multiple exponential potential is obtained when coupling vectors in exponents obey certain relations. Two subclasses of solutions…

High Energy Physics - Theory · Physics 2009-11-10 V. D. Ivashchuk , V. N. Melnikov , A. B. Selivanov

In the present manuscript the basic Einstein--Hilbert cosmological model is extended, by adding a new functional $F(G, T_{\mu\nu}T^{\mu\nu})$ in the fundamental action, encoding specific geometrical effects due to a nontrivial coupling with…

General Relativity and Quantum Cosmology · Physics 2023-05-23 Mihai Marciu , Dana Maria Ioan

In this manuscript, we present a number of fascinating explicit reconstructions for the $f(Q)$ gravity from the background of Friedmann-La\^imatre-Robertson-Walker (FLRW) evolution history. We find the more general functions of…

General Relativity and Quantum Cosmology · Physics 2022-10-25 Gaurav N. Gadbail , Sanjay Mandal , P. K. Sahoo

We address the issue of constraining the class of $f(\mathcal{R})$ able to reproduce the observed cosmological acceleration, by using the so called cosmography of the universe. We consider a model independent procedure to build up a…

General Relativity and Quantum Cosmology · Physics 2015-06-11 Alejandro Aviles , Alessandro Bravetti , Salvatore Capozziello , Orlando Luongo

The problems encountered in trying to quantize the various cosmological models, are brought forward by means of a concrete example. The Automorphism groups are revealed as the key element through which G.C.T.'s can be used for a general…

General Relativity and Quantum Cosmology · Physics 2011-07-19 T. Christodoulakis

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

Motivated by the newly proposal for gravity as the effect of the torsion scalar $T$ and trace of the energy momentum tensor $\mathcal{T}$,we investigate the cosmological reconstruction of different models of the Universe. Our aim here is to…

General Relativity and Quantum Cosmology · Physics 2018-10-09 Davood Momeni , Ratbay Myrzakulov

This paper continues a study of field theories specified for the nonuniform lattice in the finite-dimensional hypercube with the use of the earlier described deformation parameters. The paper is devoted to spontaneous breakdown and…

High Energy Physics - Theory · Physics 2009-11-10 A. E. Shalyt-Margolin

A bouncing universe is a viable candidate to solve the initial singularity problem. Here we consider bouncing solutions in the context of $f(R,\mathcal{G})$ gravity by using an order reduction technique which allows one to find solutions…

General Relativity and Quantum Cosmology · Physics 2020-06-24 Bruno J. Barros , Elsa M. Teixeira , Daniele Vernieri

The large-scale dynamics of the universe is generally described in terms of the time-dependent scale factor $a(t)$. To make contact with observational data, the $a(t)$ function needs to be related to the observable $z(r)$ function, redshift…

General Physics · Physics 2025-06-17 Jan Stenflo

Bianchi type V bulk viscous fluid cosmological models are investigated with dynamic cosmological term $\Lambda(t)$. Using a generation technique (Camci {\it et al.}, 2001), it is shown that the Einstein's field equations are solvable for…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Anirudh Pradhan , Kanti Jotania , Anju Rai

A kinematic treatment to trace out the form of $f(R)$ cosmology, within the Palatini formalism, is discussed by only postulating the universe homogeneity and isotropy. To figure this out we build model-independent approximations of the…

General Relativity and Quantum Cosmology · Physics 2019-01-07 Salvatore Capozziello , Rocco D'Agostino , Orlando Luongo

We propose a new law for the deceleration parameter that varies linearly with time and covers Berman's law where it is constant. Our law not only allows one to generalize many exact solutions that were obtained assuming constant…

General Relativity and Quantum Cosmology · Physics 2012-01-25 Ozgur Akarsu , Tekin Dereli

A new strategy for the reconstruction of $f(R)$ gravity models have been attempted using Raychaudhuri equation. Two examples, one for an eternally accelerating universe and the other for one that mimics a ${\Lambda}$CDM expansion history…

General Relativity and Quantum Cosmology · Physics 2019-04-09 Shibendu Gupta Choudhury , Ananda Dasgupta , Narayan Banerjee

Using techniques from singular perturbation theory, we explicitly calculate the cosmological evolution in a class of modified gravity models. By considering the (m)CDTT model, which aims to explain the current acceleration of the universe…

Astrophysics · Physics 2009-06-23 Jonathan D. Evans , Lisa M. H. Hall , Philippe Caillol