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We develop an approach to compute observables beyond the linear regime of dark matter perturbations for general dark energy and modified gravity models. We do so by combining the Effective Field Theory of Dark Energy and Effective Field…

Cosmology and Nongalactic Astrophysics · Physics 2020-01-07 Giulia Cusin , Matthew Lewandowski , Filippo Vernizzi

We calculate deviations in cosmological observables as a function of parameters in a class of connection-based models of quantum gravity. In this theory non-trivial modifications to the background cosmology can occur due to a distortion of…

Cosmology and Nongalactic Astrophysics · Physics 2023-02-01 Michael W. Toomey , Savvas Koushiappas , Bruno Alexandre , João Magueijo

We discuss some of the consequences of changing the matter to gravity coupling without affecting the gravitational dynamics. The Einstein tensor is usually assumed to be proportional to the stress tensor due to the divergence free property…

General Relativity and Quantum Cosmology · Physics 2013-01-15 T. Delsate , J. Steinhoff

In this contribution one examines the generalization of the $f(R)$ theories of gravity where one introduces a non-minimal coupling between curvature and matter. This model has new and interesting features. %, specially concerning the energy…

General Relativity and Quantum Cosmology · Physics 2014-11-20 Orfeu Bertolami , Miguel Carvalho Sequeira

It has been argued that a Universe governed by Eddington-Born-Infeld gravity can be compatible with current cosmological constraints. The extra fields introduced in this theory can behave both as dark matter and dark energy, unifying the…

Astrophysics · Physics 2009-04-02 Máximo Bañados , Pedro G. Ferreira , Constantinos Skordis

We consider the sector of Horndeski's gravity characterized by the coupling between the kinetic scalar field term and the Einstein tensor. We numerically construct neutron star configurations where the external geometry is identical to the…

General Relativity and Quantum Cosmology · Physics 2015-09-02 Adolfo Cisterna , Térence Delsate , Massimiliano Rinaldi

The paper studies different observational features in the case of a specific cubic gravity theory, based on third order contractions of the Riemann tensor. Considering viable cosmic chronometers data, baryon acoustic oscillations, and…

General Relativity and Quantum Cosmology · Physics 2023-11-21 Mihai Marciu , Dana Maria Ioan , Mihai Dragomir

We present modified cosmological scenarios that arise from the application of the "gravity-thermodynamics" conjecture, using the Barrow entropy instead of the usual Bekenstein-Hawking one. The former is a modification of the black hole…

General Relativity and Quantum Cosmology · Physics 2020-07-22 Emmanuel N. Saridakis

Cosmological implications of a class of hybrid metric-Palatini gravity with a non-minimal matter-geometry coupling is considered. The theory contains a metric curvature tensor, together with a curvature tensor constructed from an…

General Relativity and Quantum Cosmology · Physics 2025-12-25 Reza Jalali , Shahab Shahidi , Mohammad Hossein Zhoolideh Haghighi

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 consider perturbative modifications of the Friedmann equations in terms of energy density corresponding to modified theories of gravity proposed as an alternative route to comply with the observed accelerated expansion of the universe.…

General Relativity and Quantum Cosmology · Physics 2015-05-13 L. Fernández-Jambrina , R. Lazkoz

We discuss the possibility of explaining observations usually related to the existence of dark matter by passing from the general relativity (GR) theory to a modified theory of gravity, the embedding theory proposed by Regge and Teitelboim.…

General Relativity and Quantum Cosmology · Physics 2023-11-07 S. A. Paston

The paper studies the possible interplay between matter and geometry in scalar tensor theories of gravitation where the energy--momentum tensor is directly coupled with the Einstein tensor. After obtaining the scalar tensor representation…

General Relativity and Quantum Cosmology · Physics 2024-10-08 Mihai Marciu

In this work, I present exact cosmological solutions from Wesson's Induced Matter Model application to a general 5D metric in f(R,T) theory of gravity. The non-conservation of the energy-momentum tensor, predicted by f(R,T) theory, allows…

General Relativity and Quantum Cosmology · Physics 2015-04-23 Pedro H. R. S. Moraes

In the semi-classical regime, quantum fluctuations embedded in a Riemannian spacetime can be effectively recast as classical back reactions and manifest themselves in the form of non-minimal couplings between matter and curvature. In this…

General Relativity and Quantum Cosmology · Physics 2022-02-07 Che-Yu Chen , Yu-Hsien Kung

It has been recently proposed that gravity might be an entropic force. Although a well defined fundamental description for such a mechanism is still lacking, it is still possible to address the viability of phenomenological models of…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Miguel Zumalacarregui

The scalar-tensor representation of $f(R,T)$ gravity is extended to incorporate the Herglotz variational principle. The field equations are derived in both the geometric and scalar-tensor frameworks. Although the divergence of the…

General Relativity and Quantum Cosmology · Physics 2026-03-02 Marek Wazny

We construct a family of viable scalar-tensor models of dark energy (DE) which possess a phase of late-time acceleration preceded by a standard matter era, while at the same time satisfying the local gravity constraints (LGC). The coupling…

Astrophysics · Physics 2008-11-26 Shinji Tsujikawa , Kotub Uddin , Shuntaro Mizuno , Reza Tavakol , Jun'ichi Yokoyama

We show that in the $f(Q)$ gravity with a non-metricity scalar $Q$, the curvatures in Einstein's gravity, that is, the Riemann curvature constructed from the standard Levi-Civita connection, could not be excluded or naturally appear. The…

General Relativity and Quantum Cosmology · Physics 2024-08-16 Shin'ichi Nojiri , S. D. Odintsov

In this proceeding, we review modified theories of gravity with a curvature-matter coupling between an arbitrary function of the scalar curvature and the Lagrangian density of matter. This explicit nonminimal coupling induces a…

General Relativity and Quantum Cosmology · Physics 2022-09-20 Francisco S. N. Lobo , Tiberiu Harko