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Related papers: Constraining viscous fluid models in $f(Q)$ gravit…

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The article communicates exploration of gravitational baryogenesis in presence of $f(Q,\mathcal{ T})$ gravity where $Q$ denote the nonmetricity and $\mathcal{ T}$ the trace of the energy momentum tensor. We study various baryogenesis…

General Physics · Physics 2020-04-02 Snehasish Bhattacharjee , P. K. Sahoo

We propose a novel model in the framework of $f(Q)$ gravity, which is a gravitational modification class arising from the incorporation of non-metricity. The model has General Relativity as a particular limit, it has the same number of free…

General Relativity and Quantum Cosmology · Physics 2021-09-15 Fotios K. Anagnostopoulos , Spyros Basilakos , Emmanuel N. Saridakis

In this paper, we investigate the cosmic expansion scenarios within the framework of $f(Q,T)$ gravity by using the affine equation of state (EoS) parameter. Specifically, we consider the linear form $f(Q,T)=Q+\beta T$, where $\beta$ is a…

General Relativity and Quantum Cosmology · Physics 2026-04-24 Romanshu Garg , G. P. Singh

In this work, we investigate gravitational baryogenesis in the framework of scalar-nonmetricity theories by considering two classes of modified gravity models, namely $f(Q,\phi)=Q+\xi Q \phi^2$ and $f(Q,\phi)=\alpha Q^n + \beta \phi Q$.…

General Relativity and Quantum Cosmology · Physics 2026-05-05 F. Mavoa , M. C. Sow , M. G. Ganiou , C. S. Touré , C. R. Tefo

We study a warm inflationary model for different expansions assuming an anisotropic universe described by Bianchi I metric. The universe is filled with a scalar field or inflaton, radiation, and bulk viscous pressure. We carry out the…

General Relativity and Quantum Cosmology · Physics 2022-02-07 Mehdi Shokri , Jafar Sadeghi , Ramón Herrera , Saeed Noori Gashti

We establish constraints on $f(T)$ gravity by considering the possibility of a scenario that supports a phantom crossing of the equation of state parameter $\omega_{DE}$. After determining the viable parameter space of the model, while…

Cosmology and Nongalactic Astrophysics · Physics 2023-06-23 F. B. M. dos Santos

$f(T)$ cosmology has shown promise in explaining aspects of cosmic evolution. In this work, we analyze constraints on leading models of $f(T)$ gravity in the context of the recently released Pantheon+ data set, together with comparisons…

General Relativity and Quantum Cosmology · Physics 2023-05-22 Rebecca Briffa , Celia Escamilla-Rivera , Jackson Levi Said , Jurgen Mifsud

Some cosmological scenarios with bulk viscosity for the dark energy fluid are considered. Based on some considerations related to hydrodynamics, two different equations of state for dark energy are assumed, leading to power-law and…

General Relativity and Quantum Cosmology · Physics 2020-02-07 Sergei D. Odintsov , Diego Saez-Chillon Gomez , German S. Sharov

We investigate $f\left( Q\right) $-gravity with a matter-gravity coupling as a geometric dark energy candidate for the description of the late-time cosmic acceleration within a spatially flat Friedmann--Lema\^{\i}tre-Robertson-Walker…

General Relativity and Quantum Cosmology · Physics 2026-03-24 Andronikos Paliathanasis

In a spatially flat Friedmann-Lema\^{i}tre-Robertson-Walker universe, we investigate a unified cosmic fluid scenario endowed with bulk viscosity in which the coefficient of the bulk viscosity has a power law evolution. The power law in the…

Cosmology and Nongalactic Astrophysics · Physics 2019-11-20 Weiqiang Yang , Supriya Pan , Eleonora Di Valentino , Andronikos Paliathanasis , Jianbo Lu

We present a simple (microscopic) model in which bulk viscosity plays a role in explaining the present acceleration of the universe. The effect of bulk viscosity on the Friedmann equations is to turn the pressure into an "effective"…

Cosmology and Nongalactic Astrophysics · Physics 2011-09-23 Jean-Sebastien Gagnon , Julien Lesgourgues

We study the growth of structures in modified gravity models where the Poisson equation and the relationship between the two Newtonian potentials are modified by explicit functions of space and time. This parameterisation applies to the…

Cosmology and Nongalactic Astrophysics · Physics 2012-10-24 Philippe Brax , Patrick Valageas

Interacting fluids, endowed with bulk viscous stresses, are discussed in a unified perspective with the aim of generalizing the treatment of cosmological perturbation theory to the case where both fluctuating decay rates and fluctuating…

Astrophysics · Physics 2009-11-24 Massimo Giovannini

The present work studies one of Einstein's alternative formulations based on the non-metricity scalar $Q$ generalized as $f(Q)$ theory. More specifically, we consider the power-law form of $f(Q)$ gravity i.e. $f(Q)=Q+\alpha\, Q^n$. Here, we…

General Relativity and Quantum Cosmology · Physics 2021-05-26 Wompherdeiki Khyllep , Andronikos Paliathanasis , Jibitesh Dutta

A Bayesian statistical analysis using redshift space distortions data is performed to test a model of Symmetric Teleparallel Gravity where gravity is non-metrical. The cosmological background mimics a $\Lambda$CDM evolution but differences…

General Relativity and Quantum Cosmology · Physics 2020-06-15 Bruno J. Barros , Tiago Barreiro , Tomi Koivisto , Nelson J. Nunes

If nonrelativistic dark matter and radiation are allowed to interact, reaching an approximate thermal equilibrium, this interaction induces a bulk viscous pressure changing the effective one-fluid description of the universe dynamics,…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-18 Hermano Velten , William Iania

In this paper, we study the $f(T,\mathcal{T})$ gravity model in the presence of the bulk viscosity by the flat-FRW metric. The field equation is obtained by teleparallel gravity with tetrad field. The universe components are considered as…

General Relativity and Quantum Cosmology · Physics 2020-12-18 T. Mirzaei-Rezaei , Alireza Amani , E. Yusofi , S. Rouhani , M. A. Ramzanpour

On the basis of homogeneous and isotropic Friedmann-Lemaitre-Robertson-Walker (FLRW) geometry, solutions to the issues of cosmic acceleration and dark energy are being put forth within the context of $f\left( Q\right)$ gravity. We take into…

General Relativity and Quantum Cosmology · Physics 2023-03-28 M. Koussour , Simran Arora , Dhruba Jyoti Gogoi , M. Bennai , P. K. Sahoo

Density perturbations in the cosmic microwave background within general $f(R,\phi)$ models of gravity are investigated. The general dynamical equations for the tensor and scalar modes in any $f(R,\phi)$ gravity model are derived. An…

General Relativity and Quantum Cosmology · Physics 2017-10-11 Fayçal Hammad

In this paper, we have constructed the cosmological model of the universe in a two fluids environment with a newly developed mathematical formalism. In order to construct the model Binachi type V (BV) space time is considered with a time…

General Relativity and Quantum Cosmology · Physics 2019-01-23 B. Mishra , Pratik P Ray , R. Myrzakulov