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We propose a connection between global physics and local galactic dynamics via quantum gravity. The salient features of cold dark matter (CDM) and modified Newtonian dynamics (MOND) are combined into a unified scheme by introducing the…

General Relativity and Quantum Cosmology · Physics 2015-05-28 Chiu Man Ho , Djordje Minic , Y. Jack Ng

We investigate a modified cosmological model aimed at addressing the Hubble tension, considering revised dynamics in the late Universe. The model introduces a parameter $c$ affecting the evolution equations, motivated by a modified Poisson…

Cosmology and Nongalactic Astrophysics · Physics 2025-03-13 Luis A. Escamilla , Donatella Fiorucci , Giovanni Montani , Eleonora Di Valentino

Cosmography can be considered as a sort of a model-independent approach to tackle the dark energy/modified gravity problem. In this review, the success and the shortcomings of the $\Lambda$CDM model, based on General Relativity and standard…

General Relativity and Quantum Cosmology · Physics 2019-04-09 Salvatore Capozziello , Rocco D'Agostino , Orlando Luongo

We consider general curvature-invariant modifications of the Einstein-Hilbert action that become important only in regions of extremely low space-time curvature. We investigate the far future evolution of the universe in such models,…

We describe and demonstrate the potential of a new and very efficient method for simulating certain classes of modified gravity theories, such as the widely studied $f(R)$ gravity models. High resolution simulations for such models are…

Cosmology and Nongalactic Astrophysics · Physics 2017-03-14 Sownak Bose , Baojiu Li , Alexandre Barreira , Jian-hua He , Wojciech A. Hellwing , Kazuya Koyama , Claudio Llinares , Gong-Bo Zhao

We consider models of accelerating Universe elaborated for Finsler like gravity theories constructed on tangent bundles to Lorentz manifolds. In the osculating approximation, certain locally anisotropic configurations are similar to those…

Cosmology and Nongalactic Astrophysics · Physics 2013-03-15 Panayiotis C. Stavrinos , Sergiu I. Vacaru

Several models based on General Relativity and Modified Gravity aim to reproduce the observed universe with precision comparable to the flat-$\Lambda$CDM cosmological model. In this study, we investigate the consistency of some of these…

Cosmology and Nongalactic Astrophysics · Physics 2025-12-05 Fernanda Oliveira , Bruno Ribeiro , Wiliam S. Hipólito-Ricaldi , Felipe Avila , Armando Bernui

This research investigates the impact of modified gravity on cosmic scales, focusing on $f(Q)$ cosmology. By applying energy conditions, the study reconstructs various $f(Q)$ models, considering an accelerating Universe, quintessence, and a…

General Relativity and Quantum Cosmology · Physics 2025-04-14 Irfan Mahmood , Hira Sohail , Allah Ditta , S. H. Shekh , Anil Kumar Yadav

We demonstrate that QCD gluon amplitudes can be used to construct a Lagrangian for gravity. This procedure makes use of perturbative `squaring' relations between gravity and gauge theory that follow from string theory. We explicitly carry…

High Energy Physics - Theory · Physics 2009-10-31 Z. Bern , A. K. Grant

We investigate the metric perturbations of the restricted f(R) theory of gravity in the cosmological context and explore the phenomenological implications of this model. We show that it is possible to construct a restricted model of…

General Relativity and Quantum Cosmology · Physics 2017-04-12 M. Chaichian , A. Ghalee , J. Kluson

Alterations of the gravity Lagrangian introduced in modified torsion gravity theories---also referred to as $f(T)$ gravity---allows for an accelerated expansion in a matter dominated Universe. In this framework, the cosmic speed up is…

Cosmology and Nongalactic Astrophysics · Physics 2014-04-23 Stefano Camera , Vincenzo F. Cardone , Ninfa Radicella

In this paper, we derive the field equations of modified Gauss-Bonnet gravity termed as $f(R,G)$ gravity for the non-flat Friedmann-Robertson-Walker (FRW) spacetime. We utilize the dynamical system approach to study the cosmic dynamics of…

General Relativity and Quantum Cosmology · Physics 2025-01-22 Ashutosh Singh

We study Modified Gravity (MG) theories by modelling the redshifted matter power spectrum in a spherical Fourier-Bessel (sFB) basis. We use a fully non-linear description of the real-space matter power-spectrum and include the lowest-order…

Cosmology and Nongalactic Astrophysics · Physics 2016-01-27 Dipak Munshi , Geraint Pratten , Patrick Valageas , Peter Coles , Philippe Brax

We present an overview of a recently suggested new model of quantum initial conditions for the Universe in the form of a cosmological density matrix. This density matrix originally suggested in the Euclidean quantum gravity framework turns…

High Energy Physics - Theory · Physics 2008-11-03 A. O. Barvinsky , C. Deffayet , A. Yu. Kamenshchik

In this paper we introduce a new public Einstein-Boltzmann solver, \texttt{MGCLASS II}, built as a modification to the publicly available \texttt{CLASS} code, that allows to obtain cosmological observables for Modified Gravity theories. It…

Cosmology and Nongalactic Astrophysics · Physics 2022-06-28 Ziad Sakr , Matteo Martinelli

We use the cosmic shear data from the Canada-France-Hawaii Telescope Lensing Survey to place constraints on $f(R)$ and {\it Generalized Dilaton} models of modified gravity. This is highly complimentary to other probes since the constraints…

Cosmology and Nongalactic Astrophysics · Physics 2015-10-21 Joachim Harnois-Déraps , Dipak Munshi , Patrick Valageas , Ludovic van Waerbeke , Philippe Brax , Peter Coles , Luca Rizzo

A reconstruction of modified gravity is proposed by establishing a correspondence between the effective density of the modified gravity and the holographic density. The non-homogeneous term in the modified Friedmann equation, generated by…

General Relativity and Quantum Cosmology · Physics 2019-02-20 L. N. Granda

In this paper, we investigate and analyze the cosmological dynamics of the universe, with an effect of modified $f(R)$ gravity emerging at cosmological scale. We choose the Einstein frame as a physical frame. We consider phase portraits of…

Astrophysics · Physics 2007-05-23 Daris Samart

First, we propose a scale-invariant modified gravity interacting with a neutral scalar "inflaton" and a Higgs-like SU(2)xU(1) iso-doublet scalar field based on the formalism of non-Riemannian (metric-independent) spacetime volume-elements.…

General Relativity and Quantum Cosmology · Physics 2020-05-14 David Benisty , Eduardo Guendelman , Emil Nissimov , Svetlana Pacheva

An inhomogeneous (1+1)-dimensional model of the quantum gravity is considered. It is found, that this model corresponds to a string propagating against some curved background space. The quantization scheme including the Wheeler-DeWitt…

General Relativity and Quantum Cosmology · Physics 2015-05-28 S. L. Cherkas , V. L. Kalashnikov