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In the present chapter, we have established multiple fluid cosmological models under interaction scenarios. the interaction model we have established is a binary type of interaction scenario where three types of fluids are bound with…

General Relativity and Quantum Cosmology · Physics 2023-04-14 Alokananda Kar , Shouvik Sadhukhan

One of the challenges in testing gravity with cosmology is the vast freedom opened when extending General Relativity. For linear perturbations, one solution consists in using the Effective Field Theory of Dark Energy (EFT of DE). Even then,…

Cosmology and Nongalactic Astrophysics · Physics 2017-09-20 Jérôme Gleyzes

We investigate the future evolution of the dark energy universe in modified gravities including $F(R)$ gravity, string-inspired scalar-Gauss-Bonnet and modified Gauss-Bonnet ones, and ideal fluid with the inhomogeneous equation of state…

High Energy Physics - Theory · Physics 2009-09-17 Kazuharu Bamba , Shin'ichi Nojiri , Sergei D. Odintsov

Modified gravity is one of the most promising candidates for explaining the current accelerating expansion of the Universe, and even its unification with the inflationary epoch. Nevertheless, the wide range of models capable to explain the…

General Relativity and Quantum Cosmology · Physics 2015-06-03 Álvaro de la Cruz-Dombriz , Diego Sáez-Gómez

Analogue gravity offers an approach for testing the universality and robustness of quantum field theories in curved spacetimes and validating them using down-to-earth, laboratory-based experiments. Fluid interfaces are a promising framework…

General Relativity and Quantum Cosmology · Physics 2023-06-27 Vitor S. Barroso , Cameron R. D. Bunney , Silke Weinfurtner

We show how to fully map a specific model of modified gravity into the Einstein-Boltzmann solver EFTCAMB. This approach consists in few steps and allows to obtain the cosmological phenomenology of a model with minimal effort. We discuss all…

Cosmology and Nongalactic Astrophysics · Physics 2016-04-20 Bin Hu , Marco Raveri , Matteo Rizzato , Alessandra Silvestri

We consider various forms of action allowing us to describe a perfect fluid in the framework of General Relativity. First we consider a potential motion without pressure. Starting from an action in terms of the current density vector built…

General Relativity and Quantum Cosmology · Physics 2017-11-01 S. A. Paston

We review the effective field theory of modified gravity in which the Lagrangian involves three dimensional geometric quantities appearing in the 3+1 decomposition of space-time. On the flat isotropic cosmological background we expand a…

High Energy Physics - Theory · Physics 2015-02-24 Ryotaro Kase , Shinji Tsujikawa

The $f(Q,C)$ framework of gravity enables the depiction of an effective dark energy fluid that emerges from geometry itself, thus leading to modifications in the cosmological phenomenology of General Relativity. We pursue this approach to…

General Relativity and Quantum Cosmology · Physics 2025-12-01 Mikel Artola , Ismael Ayuso , Ruth Lazkoz , Gonzalo Olmo , Vincenzo Salzano

In this work, we introduce an effective model for both ideal and viscous fluid dynamics within the framework of kinetic field theory (KFT). The main application we have in mind is cosmic structure formation where gaseous components need to…

Statistical Mechanics · Physics 2018-11-01 C. Viermann , J. T. Schneider , R. Lilow , F. Fabis , C. Littek , E. Kozlikin , M. Bartelmann

We consider the evolution of perturbed cosmological spacetime with multiple fluids and fields in Einstein gravity. Equations are presented in gauge-ready forms, and are presented in various forms using the curvature (\Phi or \phi_\chi) and…

Astrophysics · Physics 2010-05-28 J. Hwang , H. Noh

The effective field theory of dark energy and modified gravity is supposed to well describe, at low energies, the behaviour of the gravity modifications due to one extra scalar degree of freedom. The usual curvature perturbation is very…

General Relativity and Quantum Cosmology · Physics 2017-10-11 Antonio De Felice , Noemi Frusciante , Georgios Papadomanolakis

We provide a systematic and updated discussion of a research line carried out by our group over the last few years, in which gravity is modified at cosmological distances by the introduction of nonlocal terms, assumed to emerge at an…

Cosmology and Nongalactic Astrophysics · Physics 2020-04-15 Enis Belgacem , Yves Dirian , Andreas Finke , Stefano Foffa , Michele Maggiore

We discuss a modified form of gravity implying that the action contains a power \alpha of the scalar curvature. Coupling with the cosmic fluid is assumed. As equation of state for the fluid, we take the simplest version where the pressure…

General Relativity and Quantum Cosmology · Physics 2009-11-11 I. Brevik , O. Gorbunova , Y. A. Shaido

We elaborate on nonmetric geometric flow theory and metric-affine gravity with applications in modern cosmology. Two main motivations for our research follow from the facts that 1) cosmological models for $f(Q)$ modified gravity theories,…

General Relativity and Quantum Cosmology · Physics 2024-10-08 L. Bubuianu , E. Nurlan , J. O. Seti , S. Vacaru , E. V. Veliev

We review the exact solutions in modified gravity. It is one of the main problems of mathematical physics for the gravity theory. One can obtain an exact solution if the field equations reduce to a system of ordinary differential equations.…

General Relativity and Quantum Cosmology · Physics 2013-05-27 Andrey N. Makarenko , Valery V. Obukhov

We analyse the implications of the presence of spatial curvature in modified gravity models. As it is well known, the current standard cosmological model, the $\Lambda$CDM, is assumed to be spatially flat based on the results of many…

General Relativity and Quantum Cosmology · Physics 2024-12-03 Serena Gambino , Francesco Pace

In this paper, we have considered flat Friedmann-Lema\^{i}tre-Robertson-Walker metric in the framework of perfect fluid models and modified $f(G)$ gravity (where $G$ is the Gauss Bonnet invariant). Particularly, we have considered…

General Relativity and Quantum Cosmology · Physics 2017-08-08 Kazuharu Bamba , M. Ilyas , M. Z. Bhatti , Z. Yousaf

We investigate the cosmological implications of a new class of modified gravity, where the field equations generically include higher-order derivatives of the matter fields, arising from the introduction of non-dynamical auxiliary fields in…

General Relativity and Quantum Cosmology · Physics 2016-07-01 Tiberiu Harko , Francisco S. N. Lobo , Emmanuel N. Saridakis

Effective equations are often useful to extract physical information from quantum theories without having to face all technical and conceptual difficulties. One can then describe aspects of the quantum system by equations of classical type,…

High Energy Physics - Theory · Physics 2008-11-26 Martin Bojowald , Aureliano Skirzewski