English
Related papers

Related papers: A third alternative to explain recent observations…

200 papers

In this research work, we explore the late-time accelerated expansion of the universe within the framework of modified gravity, specifically $f(R, L_m)$ theory, by considering two non-linear models: $f(R, L_{m}) = \frac{R}{2}+(1+\eta R)…

General Relativity and Quantum Cosmology · Physics 2025-06-23 Khomesh R. Patle , G. P. Singh , Romanshu Garg

We investigate the divergence-free parametric form of the deceleration parameter within the simplest non-minimal matter-geometry coupling in $f(R,T)$ gravity, where $R$ is the Ricci scalar and $T$ is the trace of the energy-momentum tensor.…

General Relativity and Quantum Cosmology · Physics 2025-03-11 A. Zhadyranova , M. Koussour , Zh. Kanibekova , V. Zhumabekova , U. Ismail , S. Muminov , J. Rayimbaev

A simple speed-up cosmology model is proposed to account for the dark energy puzzle. We condense contributions from dark energy and curvature term into one effective parameter in order to reduce parameter degeneracies and to find any…

Astrophysics · Physics 2007-10-10 Xin-He Meng , Meng Su , Zheng Wang

The eternally inflating multiverse provides a consistent framework to understand coincidences and fine-tuning in the universe. As such, it provides the possibility of finding another coincidence: if the amount of slow-roll inflation was…

High Energy Physics - Theory · Physics 2013-05-30 Alan H. Guth , Yasunori Nomura

Galaxies represent the visible fabric of the Universe and there has been considerable progress recently in both observational and theoretical studies. The underlying goal is to understand the present-day diversity of galaxy forms, masses…

Astrophysics · Physics 2007-05-23 Richard Ellis

In order to study quantum dynamics of the FRW-universe of closed type, definitions of velocity, Hubble function and duration of the evolved universe are introduced into cosmology. The proposed definitions are characterized by high stability…

General Relativity and Quantum Cosmology · Physics 2014-05-23 Sergei P. Maydanyuk

It is shown that a present acceleration with a past deceleration is a possible solution of the Friedmann equation by considering the Universe as a mixture of a scalar with a matter field and by including a non-equilibrium pressure term in…

General Relativity and Quantum Cosmology · Physics 2009-11-07 G. M. Kremer , F. P. Devecchi

We have considered a cosmological model with a phenomenological model for the cosmological constant of the form $\Lambda=\bt\fr{\ddot R}{R}$, $ \bt$ is a constant. For age parameter consistent with observational data the Universe must be…

General Relativity and Quantum Cosmology · Physics 2017-08-23 Arbab I. Arbab

In this study, we investigate the cosmological history within the framework of modified $f(Q)$ gravity, which proposes an alternative theory of gravity where the gravitational force is described by a non-metricity scalar. By employing a…

General Relativity and Quantum Cosmology · Physics 2023-08-30 N. Myrzakulov , M. Koussour , A. Mussatayeva

In this paper we discuss a cosmological model for a universe with self-regulating features. We set up the theoretical framework for the model and determine the time evolution of the scale-factor $a(t)$. It is shown that such a universe…

General Relativity and Quantum Cosmology · Physics 2024-01-15 Manasse R. Mbonye

Here $f(R)$-cosmology is discussed using a different approach. This model explains early-inflation, emergence of cosmic background radiation at the exit from inflation, cosmic deceleration during radiation-dominance followed by deceleration…

General Relativity and Quantum Cosmology · Physics 2008-10-09 S. K. Srivastava

The evolution of the quintessence in various stages of the universe, the radiation-, matter-, and quintessence-dominated, is closely related with the tracking behavior and the deceleration parameter of the universe. We gave the explicit…

Astrophysics · Physics 2008-11-26 De-Hai Zhang

The objective of the present work is to study a cosmological model for a spatially flat Universe whose constituents are a dark energy field and a matter field which includes baryons and dark matter. The constituents are supposed to be in…

General Relativity and Quantum Cosmology · Physics 2013-09-13 Gilberto M. Kremer , Octavio A. S. Sobreiro

A large number of recent observational data strongly suggest that we live in a flat, accelerating Universe composed of $\sim$ 1/3 of matter (baryonic + dark) and $\sim$ 2/3 of an exotic component with large negative pressure, usually named…

Astrophysics · Physics 2015-06-24 J. A. S. Lima

As an alternative to the paradigm of slow roll inflation, we propose an extended scenario of the matter bounce cosmology in which the Universe has experienced a quasi-matter contracting phase with a variable background equation of state…

General Relativity and Quantum Cosmology · Physics 2015-09-04 Jaume de Haro , Yi-Fu Cai

Among various phenomenological $\Lambda$ models, a time-dependent model $\dot \Lambda\sim H^3$ is selected here to investigate the $\Lambda$-CDM cosmology. Using this model the expressions for the time-dependent equation of state parameter…

General Relativity and Quantum Cosmology · Physics 2011-01-25 Saibal Ray , Maxim Khlopov , Utpal Mukhopadhyay , Partha Pratim Ghosh

We deepen the analysis of the cosmological acceleration produced by quantum gravity dynamics in the formalism of group field theory condensate cosmology, treated at the coarse-grained level via a phenomenological model, in the language of…

General Relativity and Quantum Cosmology · Physics 2025-06-19 Daniele Oriti , Xiankai Pang

We have probed a cosmological model in $f(R)$-gravity, which is a cubic equation in scalar curvature $R$. The terms arise due to nonlinear $f(R)$ function are treated as energy due to curvature inspired geometry. As a result, we find…

General Relativity and Quantum Cosmology · Physics 2023-05-03 G. K. Goswami , Rita Rani , Harshna Balhara , J. K. Singh

The warm inflation scenario is an alternative mechanism which can explain the isotropic and homogeneous Universe which we are living in. In this work I extend a previously introduced formalism, without the restriction of slow - roll regime.…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Mauricio Bellini

We investigate the cosmic evolution of the Universe across different cosmological epochs in exponential Weyl-type $f(Q, T)$ gravity model. The theoretical analysis involves a detailed dynamical system approach, where we define dimensionless…

General Relativity and Quantum Cosmology · Physics 2025-09-10 Rahul Bhagat , Francisco Tello-Ortiz , B. Mishra