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In this work we study the dynamics of universe in $f(R)=\sqrt{R^2-R_{0}^2}$ modified gravity with Palatini formalism. We use data from recent observations as Supernova Type Ia (SNIa) Gold sample and Supernova Legacy Survey (SNLS) data, size…

天体物理学 · 物理学 2008-12-18 M. Sadegh Movahed , Shant Baghram , Sohrab Rahvar

We present the first formulation of the recently proposed $f(R,\mathcal{L}_m,T)$ theory of gravity within the Palatini formalism, a well-known alternative variational approach where the metric and connection are treated as independent…

广义相对论与量子宇宙学 · 物理学 2024-11-26 J. G. de Lima Júnior , P. H. R. S. Moraes , E. Brito , J. A. S. Fortunato

We make a systematic study of the cosmological dynamics for a number of f(R) gravity theories in Palatini formalism. We find a number of interesting results: (i) models based on theories of the type (a) f(R)=R-beta R^n and (b) f(R)=R+alpha…

天体物理学 · 物理学 2008-11-26 Stephane Fay , Reza Tavakol , Shinji Tsujikawa

We introduce in $f(R)$ gravity--Palatini formalism the method of inverse problem to extract the action from the expansion history of the universe. First, we use an ansatz for the scale factor and apply the inverse method to derive an…

宇宙学与河外天体物理 · 物理学 2010-05-28 Shant Baghram , Sohrab Rahvar

In this study, we investigate a Palatini $f(R)$ gravity model featuring a quadratic term correction, aligning it with the most recent expansion rate data, with a particular focus on the latest SNIa and BAO data. Our analysis employs CC data…

广义相对论与量子宇宙学 · 物理学 2024-01-10 Débora Aguiar Gomes , Rebecca Briffa , Aleksander Kozak , Jackson Levi Said , Margus Saal , Aneta Wojnar

Alternative theories of gravity have been recently studied in connection with their cosmological applications, both in the Palatini and in the metric formalism. The aim of this paper is to propose a theoretical framework (in the Palatini…

广义相对论与量子宇宙学 · 物理学 2008-11-26 Gianluca Allemandi , Mauro Francaviglia , Matteo Luca Ruggiero , Angelo Tartaglia

We study new FRW type cosmological models of modified gravity treated on the background of Palatini approach. These models are generalization of Einstein gravity by the presence of a scalar field non-minimally coupled to the curvature. The…

广义相对论与量子宇宙学 · 物理学 2012-03-13 A. Borowiec , M. Kamionka , A. Kurek , M. Szydlowski

In this work, we study the large scale structure formation in the modified gravity in the framework of Palatini formalism and compare the results with the equivalent smooth dark energy models as a tool to distinguish between these models.…

宇宙学与河外天体物理 · 物理学 2011-01-27 Shant Baghram , Sohrab Rahvar

We demonstrate that it is possible to test models of gravity, such as Palatini $f(R)$ and Eddington-inspired Born-Infeld models, using seismic data from Earth. By incorporating additional limitations on Earth's moment of inertia and mass…

广义相对论与量子宇宙学 · 物理学 2023-08-25 Aleksander Kozak , Aneta Wojnar

One of the most favourable extensions of General Relativity is the $f(R)$ gravity. $f(R)$ gravity in Palatini formalism can be a realistic alternative to the dark energy problem. In this work we study a recently introduced dark energy…

广义相对论与量子宇宙学 · 物理学 2022-05-20 Dhruba Jyoti Gogoi , Umananda Dev Goswami

We consider the Palatini formalism of gravity with cosmological constant $\Lambda$ coupled to a scalar field $\phi$ in $n$-dimensions. The $n$-dimensional Einstein equations with $\Lambda$ can be derived by the variation of the coupled…

广义相对论与量子宇宙学 · 物理学 2009-11-11 Muxin Han , Yongge Ma , You Ding , Li Qin

Modified gravity provides a possible explanation for the currently observed cosmic accelaration. In this paper, we study general classes of modified gravity models. The Einstein-Hilbert action is modified by using general functions of the…

天体物理学 · 物理学 2008-11-26 Antonio De Felice , Pia Mukherjee , Yun Wang

Modified $f(R)$ gravity in the Palatini approach has been presently applied to Cosmology as a realistic alternative to dark energy. In this concern, a number of authors have searched for observational constraints on several $f(R)$ gravity…

天体物理学 · 物理学 2009-06-23 F. C. Carvalho , E. M. Santos , J. S. Alcaniz , J. Santos

We derive the field equations and the equations of motion for massive test particles in modified theories of gravity with an arbitrary coupling between geometry and matter by using the Palatini formalism. We show that the independent…

广义相对论与量子宇宙学 · 物理学 2011-07-05 Tiberiu Harko , Tomi S. Koivisto , Francisco S. N. Lobo

We investigate the viability of f(R) theories in the framework of the Palatini approach as solutions to the problem of the observed accelerated expansion of the universe. Two physically motivated popular choices for f(R) are considered:…

天体物理学 · 物理学 2009-11-10 S. Capozziello , V. F. Cardone , M. Francaviglia

Modified gravity, known as $f(R)$ gravity, has presently been applied to Cosmology as a realistic alternative to dark energy. For this kind of gravity the expansion of the Universe may accelerate while containing only baryonic and cold dark…

宇宙学与河外天体物理 · 物理学 2012-05-01 N. Pires , J. Santos , J. S. Alcaniz

Recently, corrections to the standard Einstein-Hilbert action are proposed to explain the current cosmic acceleration in stead of introducing dark energy. In the Palatini formulation of those modified gravity models, there is an important…

高能物理 - 理论 · 物理学 2008-11-26 Xin-He Meng , Peng Wang

As an important candidate gravity theory alternative to dark energy, a class of $f(R)$ modified gravity, which introduces a perturbation of the Ricci scalar $R$ in the Einstein-Hilbert action, has been extensively applied to cosmology to…

宇宙学与河外天体物理 · 物理学 2018-07-18 Tengpeng Xu , Shuo Cao , Jingzhao Qi , Marek Biesiada , Xiaogang Zheng , Zong-Hong Zhu

We study modified theories of gravity of the f(R) type in Palatini formalism. For a generic f(R) lagrangian, we show that the metric can be solved as the product of a scalar function times a rank-two tensor (or auxiliary metric). The scalar…

广义相对论与量子宇宙学 · 物理学 2008-11-26 Gonzalo J. Olmo

We investigate the modified gravity theories in terms of the effective dark energy models. We compare the cosmic expansion history and the linear growth in different models. We also study the evolution of linear cosmological perturbations…

广义相对论与量子宇宙学 · 物理学 2008-11-26 Seokcheon Lee
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