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相关论文: Constraining $f(Q, L_m)$ gravity with bulk viscosi…

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In this paper, we study the cosmological evolution of a viscous dark energy model within the framework of $f(Q, C)$ gravity, utilizing a two-fluid approach. The model incorporates non-metricity and boundary contributions to the total…

广义相对论与量子宇宙学 · 物理学 2025-10-15 N. Myrzakulov , Anirudh Pradhan , S. H. Shekh

In this work, we investigate the late-time cosmic dynamics in the framework of non-linear $f(R, L_m)$ gravity, adopting the functional form $f(R,L_m)=\frac{R}{2}+L_m^2$. To explore the dark energy behavior, we assume an oscillatory…

广义相对论与量子宇宙学 · 物理学 2025-11-25 Amit Samaddar , S. Surendra Singh

In this work, we consider an extension of symmetric teleparallel gravity, namely, $f(Q)$ gravity, where the fundamental block to describe spacetime is the nonmetricity, $Q$. Within this formulation of gravitation, we perform an…

广义相对论与量子宇宙学 · 物理学 2019-11-15 Ruth Lazkoz , Francisco S. N. Lobo , María Ortiz-Baños , Vincenzo Salzano

In this paper, we introduce bulk viscosity in the formalism of modified gravity theory in which the gravitational action contains a general function $f(R,T)$, where $R$ and $T$ denote the curvature scalar and the trace of the…

广义相对论与量子宇宙学 · 物理学 2015-03-02 C. P. Singh , Pankaj Kumar

This study explores a distinctive logarithmic parameterization of the deceleration parameter within the $f(Q, C)$ gravity framework, incorporating a nonlinear functional form $f(Q, C) = \gamma_1 Q^n + \gamma_2 C$, where $Q$ and $C$ denote…

广义相对论与量子宇宙学 · 物理学 2025-06-03 S. R. Bhoyar , Yash B. Ingole

In this paper, a cosmological model of the Universe is presented in $f(Q,T)$ gravity and the parameters are constrained by cosmological data sets. Initially, a generalised form of $f(Q,T)$ model is used as $f(Q,T)=-\lambda_{1}…

广义相对论与量子宇宙学 · 物理学 2024-03-21 A. S. Agrawal , B. Mishra , S. K. Tripathy

In this study, we investigate the dynamics of the Universe during the observed late-time acceleration phase within the framework of the Weyl-type $f(Q,T)$ theory. Specifically, we consider a well-motivated model with the functional form…

宇宙学与河外天体物理 · 物理学 2024-01-23 M. Koussour , S. Myrzakulova , N. Myrzakulov

In this paper, we explore modified gravity in the framework of $f(R, \mathcal{L}_m)$ theories by reconstructing the function $f(\mathcal{L}_m)$, where $\mathcal{L}_m = \rho$ is the matter Lagrangian, under the assumption of a pressureless,…

广义相对论与量子宇宙学 · 物理学 2025-06-12 Y. Kalpana Devi , S. A. Narawade , B. Mishra

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…

广义相对论与量子宇宙学 · 物理学 2026-03-24 Andronikos Paliathanasis

In this investigation, we perform an observational statistical analysis in the theory of $ f(R, L_m) $ gravity. The proposed theoretical model is based on the Ricci scalar's non-linear contribution. We use a distinct parameterization for…

广义相对论与量子宇宙学 · 物理学 2024-08-30 J. K. Singh , Shaily , Akanksha Singh , Harshna Balhara , Joao R. L. Santos

In this paper, we explore the model of $f(Q,T)$ gravity, an extension of symmetric teleparallel gravity where the nonmetricity scalar $Q$ is non-minimally coupled to the trace of the energy-momentum tensor $T$. To ensure general covariance…

广义相对论与量子宇宙学 · 物理学 2025-09-09 Rahul Bhagat , Santosh V. Lohakare , B. Mishra

In this work, we investigate the cosmological dynamics of the $f(R, \mathcal{L}_m)$ gravity framework with a particular focus on the contributions of the scalar field. Considering a functional form that includes linear and exponential…

广义相对论与量子宇宙学 · 物理学 2026-04-01 Y. Kalpana Devi , Rahul Bhagat , B. Mishra

In this article, the bulk viscosity is introduced in a modified gravity model. The gravitational action has a general $f(R,T)$ form, where $R$ and $ T $ are the curvature scalar and the trace of energy momentum tensor respectively. An…

广义相对论与量子宇宙学 · 物理学 2020-10-02 Simran Arora , Xin-he Meng , S. K. J. Pacif , P. K. Sahoo

We discuss a cosmology in which cold dark-matter particles decay into relativistic particles. We argue that such decays could lead naturally to a bulk viscosity in the cosmic fluid. For decay lifetimes comparable to the present hubble age,…

天体物理学 · 物理学 2008-11-26 James R. Wilson , Grant J. Mathews , George M. Fuller

Motivated by anomalies in cosmic microwave background observations, we investigate the implications of $f(Q, T)$ gravity in Bianchi type-I spacetime, aiming to characterize the universe's spatially homogeneous and anisotropic properties. By…

宇宙学与河外天体物理 · 物理学 2024-09-30 A. Zhadyranova , M. Koussour , V. Zhumabekova , O. Donmez , S. Muminov , J. Rayimbaev

In this paper, bulk viscosity is introduced in new holographic dark energy (HDE) to describe the effects of cosmic non-perfect fluid on the evolution of the universe in modified $f(R,T)$ gravity. Assuming $f(R,T)=R+\lambda T$, where $R$ is…

广义相对论与量子宇宙学 · 物理学 2018-04-17 C P Singh , Milan Srivastava

The recently proposed $f(Q, T)$ gravity (Xu et al. Eur. Phys. J. C \textbf{79} (2019) 708) is an extension of the symmetric teleparallel gravity. The gravitational action $L$ is given by an arbitrary function $f$ of the non-metricity $Q$…

广义相对论与量子宇宙学 · 物理学 2020-10-02 Simran Arora , P. K. Sahoo

We have investigated the accelerating behaviour of the universe in $f(Q,T)$ gravity in an isotropic and homogeneous space-time. We have initially derive the dynamical parameters in the general form of $f(Q,T)=\alpha Q^{m}+\beta T$ [Xu et…

广义相对论与量子宇宙学 · 物理学 2023-05-31 Laxmipriya Pati , S. A. Narawade , S. K. Tripathy , B. Mishra

Cosmological inflation remains a key paradigm for explaining the earliest stages of the Universe, yet the theoretical limitations of General Relativity (GR) motivate the development of alternative formulations capable of addressing both…

广义相对论与量子宇宙学 · 物理学 2025-11-13 Maryam Shiravand , Saeed Fakhry , Javad T. Firouzjaee , Ali Tizfahm

We study the late acceleration of the universe by incorporating bulk viscous matter with the running vacuum. The vacuum energy density varies as the squares of the Hubble parameter ($\rho_{\Lambda}\propto H^2$), and the coefficient of bulk…

广义相对论与量子宇宙学 · 物理学 2022-04-27 Sarath N , Jerin Mohan N D , Titus K Mathew