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We investigate the dynamics and the phase-space evolution for the scalar nonmetricity cosmology with a Chameleon mechanism. In particular, we consider a spatially flat Friedmann--Lema\^{\i}tre--Robertson--Walker geometry and within the…

General Relativity and Quantum Cosmology · Physics 2024-07-09 Andronikos Paliathanasis

We construct a cosmological scalar-tensor-theory model in which the Brans-Dicke type scalar $\Phi$ enters the effective (Jordan-frame) Hubble rate as a simple modification of the Hubble rate of the $\Lambda$CDM model. This allows us to…

General Relativity and Quantum Cosmology · Physics 2016-12-07 W. C. Algoner , H. E. S. Velten , W. Zimdahl

We investigate the dynamics of the chameleonic Generalised Brans--Dicke model in flat FRW cosmology. In a new approach, a framework to study stability and attractor solutions in the phase space is developed for the model by simultaneously…

General Relativity and Quantum Cosmology · Physics 2015-03-13 H. Farajollahi , A. Salehi

Scale transformations of cosmological models based on a statistical system of degenerate fermions with a scalar Higgs interaction are studied. The similarity properties of cosmological models are revealed under the scale transformation of…

General Relativity and Quantum Cosmology · Physics 2024-05-24 Yu. G. Ignat'ev

In this work we review the issue of imposing the conservation of the energy-momentum tensor as a necessary condition to recover the equivalence between the unimodular gravity and General Relativity (GR) equipped with a cosmological…

General Relativity and Quantum Cosmology · Physics 2022-06-29 Júlio C. Fabris , Marcelo H. Alvarenga , Mahamadou Hamani-Daouda , Hermano Velten

We consider $f(R)$ modified gravity theory incorporating the chameleon mechanism to address galactic dynamics. By employing the metric formalism and utilizing a conformal transformation, we simplify the field equations and describe the…

General Relativity and Quantum Cosmology · Physics 2024-09-04 Gayatri Mohan , Umananda Dev Goswami

Future observations of the large-scale structure have the potential to investigate cosmological models with a high degree of complexity, including the properties of gravity on large scales, the presence of a complicated dark energy…

Cosmology and Nongalactic Astrophysics · Physics 2019-02-26 Robert Reischke , Alessio Spurio Mancini , Björn Malte Schäfer , Philipp M. Merkel

In this work, the quark-hadron phase transition in a chameleon Brans-Dicke model of brane world cosmology within an effective model of QCD is investigated. Whereas, in the chameleon Brans-Dicke model of brane world cosmology, the Friedmann…

General Physics · Physics 2014-01-21 Kh. Saaidi , A. Mohammadi , T. Golanbari , H. Sheikhahmadi , B. Ratra

Recent studies by Sol\`a Peracaula, G\'omez-Valent, de Cruz P\'erez and Moreno-Pulido (2019,2020) have pointed out the intriguing possibility that Brans-Dicke cosmology with constant vacuum energy density (BD-$\Lambda$CDM) may be able to…

Cosmology and Nongalactic Astrophysics · Physics 2021-10-04 Adrià Gómez-Valent , Prajwal Hassan Puttasiddappa

Recently, the scalar-tensor representation of $f (R,T)$ gravity was used to explore gravitationally induced particle production/annihilation. Using the framework of irreversible thermodynamics of open systems in the presence of matter…

General Relativity and Quantum Cosmology · Physics 2023-10-20 Amine Bouali , Himanshu Chaudhary , Tiberiu Harko , Francisco S. N. Lobo , Taoufik Ouali , Miguel A. S. Pinto

Gauss-Bonnet-dilatonic coupling in four dimension plays an important role to explain late time cosmic evolution. However, this term is an outcome of low energy string effective action and thus ought to be important in the early universe…

General Relativity and Quantum Cosmology · Physics 2017-05-16 Subhra Debnath , Soumendra Nath Ruz , Ranajit Mandal , Abhik Kumar Sanyal

We study the cosmological evolution of the field equations in the context of Einstein-Aether cosmology by including a scalar field in a spatially flat Friedmann--Lema\^{\i}tre--Robertson--Walker spacetime. Our analysis is separated into two…

General Relativity and Quantum Cosmology · Physics 2020-01-17 Andronikos Paliathanasis , G. Papagiannopoulos , Spyros Basilakos , John D. Barrow

The derivation of conservation laws and invariant functions is an essential procedure for the investigation of nonlinear dynamical systems. In this study we consider a two-field cosmological model with scalar fields defined in the Jordan…

General Relativity and Quantum Cosmology · Physics 2021-09-14 Antonios Mitsopoulos , Michael Tsamparlis , Genly Leon , Andronikos Paliathanasis

We study flat Friedmann-Lemaitre-Robertson-Walker cosmological models for a scalar field coupled nonminimally to teleparallel gravity with generic coupling and potential functions. The goal of this paper is to determine the conditions under…

General Relativity and Quantum Cosmology · Physics 2016-08-08 Laur Jarv , Alexey Toporensky

We apply cosmological reconstruction methods to the $f(R,T)$ modified gravity, in its recently developed scalar-tensor representation. We do this analysis assuming a perfect fluid in a Friedmann-Lema\^{i}tre-Robsertson-Walker (FLRW)…

General Relativity and Quantum Cosmology · Physics 2024-07-24 Tiago B. Gonçalves , João Luís Rosa , Francisco S. N. Lobo

We discuss the evolution of cosmological tensor perturbations in the RSII model. In Gaussian normal coordinates the wave equation is non-separable, so we use the near-brane limit to perform the separation and study the evolution of…

High Energy Physics - Theory · Physics 2009-11-10 R. A. Battye , C. van de Bruck , A. Mennim

Generalized Friedmann equations governing the cosmological evolution inside a thick brane embedded in a five-dimensional Anti-de Sitter spacetime are derived. These equations are written in terms of four-dimensional effective brane…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Philippe Mounaix , David Langlois

A mathematical model is formulated for the evolution of plane perturbations in a cosmological two-component statistical system of completely degenerate scalarly charged fermions with an asymmetric scalar Higgs interaction. A complete closed…

General Relativity and Quantum Cosmology · Physics 2023-02-08 Yu. G. Ignat'ev

In a class of non-singular cosmologies derived from higher-order corrections to the low-energy bosonic string action, we derive evolution equations for the most general cosmological scalar, vector and tensor perturbations. In the large…

Astrophysics · Physics 2009-11-06 Cyril Cartier , Jai-chan Hwang , Edmund J. Copeland

We study the thermodynamics of some cosmological models based on modified gravity, a braneworld with induced gravity and curvature effect. Dark energy component seems necessary if the models are to approach thermal equilibrium in the long…

General Relativity and Quantum Cosmology · Physics 2011-09-16 Ninfa Radicella , Diego Pavón
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