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A generalization of General Relativity is studied. The standard Einstein-Hilbert action is considered in the Palatini formalism, where the connection and the metric are independent variables, and the connection is not symmetric. As a result…

General Relativity and Quantum Cosmology · Physics 2018-03-21 N. V. Kharuk , S. A. Paston , A. A. Sheykin

Alternative gravitational theories described by Lagrangians depending on general functions of the Ricci scalar have been proven to give coherent theoretical models to describe the experimental evidence of the acceleration of universe at…

High Energy Physics - Theory · Physics 2011-07-19 G. Allemandi , A. Borowiec , M. Francaviglia

Cosmological models based on f(R)-gravity may exhibit a natural acceleration mechanism without introducing a dark energy component. In this paper, we investigate cosmological consequences of the so-called Hu-Sawicki f(R)-gravity in the…

Cosmology and Nongalactic Astrophysics · Physics 2012-12-13 B. Santos , M. Campista , J. Santos , J. S. Alcaniz

The gravitational field equations on cosmological scales are obtained by averaging the Einstein field equations of general relativity. By assuming spatial homogeneity and isotropy on the largest scales, the local inhomogeneities affect the…

General Relativity and Quantum Cosmology · Physics 2007-05-23 A. A. Coley

We investigate Palatini $f(\mathcal{R},\mathcal{L}_m, \mathcal{R}_{\mu\nu}T^{\mu\nu})$ modified theories of gravity wherein the metric and affine connection are treated as independent dynamical fields and the gravitational Lagrangian is…

General Relativity and Quantum Cosmology · Physics 2019-06-26 Matthew S. Fox

The debate on the physical relevance of conformal transformations can be faced by taking the Palatini approach into account to gravitational theories. We show that conformal transformations are not only a mathematical tool to disentangle…

High Energy Physics - Theory · Physics 2009-11-10 Gianluca Allemandi , Monica Capone , Salvatore Capozziello , Mauro Francaviglia

We propose a novel theory of gravity that by construction is renormalizable, evades Ostragadsky's no-go theorem, is locally scale-invariant in the high-energy limit, and equivalent to general relativity in the low-energy limit. The theory…

General Relativity and Quantum Cosmology · Physics 2020-07-13 Daniel Coumbe

We present a novel approach to modified theories of gravity that consists of adding to the Einstein-Hilbert Lagrangian an f(R) term constructed a la Palatini. Using the respective dynamically equivalent scalar-tensor representation, we show…

General Relativity and Quantum Cosmology · Physics 2012-04-26 Tiberiu Harko , Tomi S. Koivisto , Francisco S. N. Lobo , Gonzalo J. Olmo

It is shown that a quadratic gravitational Lagrangian in the Palatini formulation is able to capture different aspects of quantum gravity phenomenology in a single framework. In particular, in this theory field excitations propagating with…

General Relativity and Quantum Cosmology · Physics 2015-06-03 Gonzalo J. Olmo

Recently, corrections of the $L(R)$ type to Einstein-Hilbert action that become important at small curvature are proposed. Those type of models intend to explain the observed cosmic acceleration without dark energy. We derive the full…

Astrophysics · Physics 2009-11-10 Xinhe Meng , Peng Wang

We examine the relationship between Palatini-like theories of gravity and models incorporating linear generalized uncertainty principles. Additionally, we delve into the thermodynamics of systems comprising both Bose and Fermi gases. Our…

General Relativity and Quantum Cosmology · Physics 2024-04-05 Aneta Wojnar , Débora Aguiar Gomes

We use astrophysical data to shed light on fundamental physics by constraining parametrized theoretical cosmological and gravitational models. Gravitational parameters are those constants that parametrize possible departures from Einstein's…

Astrophysics · Physics 2008-08-18 Yi Mao

We consider, in Palatini formalism, a modified gravity of which the scalar field derivative couples to Einstein tensor. In this scenario, Ricci scalar, Ricci tensor and Einstein tensor are functions of connection field. As a result, the…

General Relativity and Quantum Cosmology · Physics 2018-03-20 Narakorn Kaewkhao , Burin Gumjudpai

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…

General Relativity and Quantum Cosmology · Physics 2022-05-20 Dhruba Jyoti Gogoi , Umananda Dev Goswami

I review recent results obtained for extensions of general relativity formulated within the Palatini formalism, an approach in which metric and connection are treated as independent geometrical entities. The peculiar dynamics of these…

General Relativity and Quantum Cosmology · Physics 2011-12-08 Gonzalo J. Olmo

General Relativity assumes that spacetime is fully described by the metric alone. An alternative is the so called Palatini formalism where the metric and the connections are taken as independent quantities. The metric-affine theory of…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Thomas P. Sotiriou , Stefano Liberati

We formulate quantum field theories of massive fields of arbitrary spins. The presence of both physical and fake particles, organized into multiplets, makes it possible to fulfill the requirements of locality, unitarity and…

High Energy Physics - Theory · Physics 2020-07-28 Damiano Anselmi

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…

Cosmology and Nongalactic Astrophysics · Physics 2012-05-01 N. Pires , J. Santos , J. S. Alcaniz

We present an introduction to cosmic inflation in the framework of Palatini gravity, which provides an intriguing alternative to the conventional metric formulation of gravity. In the latter, only the metric specifies the spacetime…

General Relativity and Quantum Cosmology · Physics 2025-01-23 Ioannis D. Gialamas , Alexandros Karam , Thomas D. Pappas , Eemeli Tomberg

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.…

Cosmology and Nongalactic Astrophysics · Physics 2011-01-27 Shant Baghram , Sohrab Rahvar