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We present a broad and simple class of scalar-tensor scenarios that successfully realize dynamical damping of the effective cosmological constant, therefore providing a viable dynamical solution to the fine-tuning or "old" cosmological…

General Relativity and Quantum Cosmology · Physics 2018-12-27 Oleg Evnin , Kévin Nguyen

Understanding the evolution of dark energy poses a significant challenge in modern cosmology, as it is responsible for the universe's accelerated expansion. In this study, we focus on a specific $f(T)$ cosmological model and analyze its…

Cosmology and Nongalactic Astrophysics · Physics 2024-05-14 A. Zhadyranova , M. Koussour , S. Bekkhozhayev , V. Zhumabekova , J. Rayimbaev

It has been recently proposed that gravity might be an entropic force. Although a well defined fundamental description for such a mechanism is still lacking, it is still possible to address the viability of phenomenological models of…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Miguel Zumalacarregui

In a thermodynamical model of cosmological FLRW event horizons for the dark energy (DE), we consider a logarithmic corrective term in the entropy to which corresponds a new term in the DE density. This model of $\Lambda (t)$ in an…

Astrophysics · Physics 2016-08-15 Cécile Barbachoux , Jérome Gariel , Gérard Le Denmat

A new approach for arbitrary dimension to the Friedmann cosmological models is presented. Taking suitable changes of the parameters of the spacetime the harmonic motion equations appear, where the curvature determines the angular frequency.…

General Relativity and Quantum Cosmology · Physics 2014-03-03 Rafael M. Rubio , Juan J. Salamanca

Recently, zero-point length cosmology has shown some positive insights into some non-singular aspects of the early Universe. In addition, topological defects are known to play a significant role by its presence as a part of the total energy…

General Relativity and Quantum Cosmology · Physics 2025-05-21 Kalyan Bhuyan , Mrinnoy M. Gohain

In this paper a new theory of Dark Matter is proposed. Experimental analysis of several Galaxies show how the non-gravitational contribution to galactic Velocity Rotation Curves can be interpreted as that due to the Cosmological Constant…

Astrophysics · Physics 2007-05-23 G. V. Kraniotis , S. B. Whitehouse

A new phenomenological dark energy model, originally associated to the large-scale structure formation and considered as a solution to the fine-tuning and coincidence problems related to the cosmological constant, was analyzed within the…

General Relativity and Quantum Cosmology · Physics 2026-03-05 A. Kazım Çamlıbel

It has recently been realized that many theories of physics beyond the Standard Model give rise to cosmological histories exhibiting extended epochs of cosmological stasis. During such epochs, the abundances of different energy components…

Cosmology and Nongalactic Astrophysics · Physics 2024-12-17 Keith R. Dienes , Lucien Heurtier , Fei Huang , Tim M. P. Tait , Brooks Thomas

In this paper, a cosmological solution to Mimetic Dark Matter (MDM) for an exponential potential is provided. Then, a solution for the $0-i$ perturbed Einstein's differential equation of MDM is obtained based on an exponential potential…

General Relativity and Quantum Cosmology · Physics 2017-03-22 Hassan Saadi

We consider scalar perturbations of energy-density for a class of cosmological models where an early phase of accelerated expansion evolves, without any fine-tuning for graceful exit, towards the standard Friedman eras of observed universe.…

General Relativity and Quantum Cosmology · Physics 2011-05-10 S. Capozziello , G. Lambiase , G. Scarpetta

Cosmological inflation is not the only early universe scenario consistent with current observational data. I will discuss the criteria for a successful early universe cosmology, compare a couple of the proposed scenarios (inflation,…

High Energy Physics - Theory · Physics 2019-11-15 Robert Brandenberger

The South Pole Telescope (SPT), Atacama Cosmology Telescope (ACT), and Wilkinson Microwave Anisotropy Probe (WMAP) have each reported measurements of the cosmic microwave background's (CMB) angular power spectrum which favor the existence…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-30 Dan Hooper , Farinaldo S. Queiroz , Nickolay Y. Gnedin

In modern cosmology, the curiosity of ultimately understanding the nature of the dark energy controlling the recent acceleration of the Universe motivates us to explore its properties by using some novel approaches. In this work, to explore…

General Relativity and Quantum Cosmology · Physics 2023-12-19 Sanjay Mandal , Sneha Pradhan , P. K. Sahoo , Tiberiu Harko

Using only the standard considerations of spacetime foam and the Euclidean Quantum Gravity techniques known long ago, we result to a model of Topological Dark Energy (TDE) that outperforms the standard $\Lambda$CDM paradigm with regard to…

General Relativity and Quantum Cosmology · Physics 2025-07-25 Fotios K. Anagnostopoulos , Stylianos A. Tsilioukas , Emmanuel N. Saridakis

Recent observations of the Universe have led to a conclusion suppressing an up-to-now supposed deceleration of the Universe caused by attractive gravitational forces. Contrary, there is a renaissance of the cosmological member lambda and…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Jozef Sima , Miroslav Sukenik

Based on an earlier introduced new class of generalized gravity-matter models defined in terms of two independent non-Riemannian volume forms (alternative generally covariant integration measure densities) on the space-time manifold, we…

High Energy Physics - Theory · Physics 2016-11-29 Eduardo Guendelman , Ramon Herrera , Pedro Labrana , Emil Nissimov , Svetlana Pacheva

We analyze two different scenarios for the late Universe dynamics, resulting into Hubble parameters deviating from the $\Lambda$CDM, mainly for the presence of an additional free parameter, which is the dark energy parameter. The first…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-04 Giovanni Montani , Elisa Fazzari , Nakia Carlevaro , Maria Giovanna Dainotti

In order to explain the Late-times accelerated expansion of the Universe we must appeal to some form of Dark Energy. In the standard model of cosmology, the latter is interpreted as a Cosmological Constant $\Lambda$. However, for a number…

General Relativity and Quantum Cosmology · Physics 2021-02-18 Leonardo Giani

The tensions between the values of Hubble constant obtained from the early and the late Universe data pose a significant challenge to modern cosmology. Possible modifications of the flat homogeneous isotropic cosmological {\Lambda}CDM model…

Cosmology and Nongalactic Astrophysics · Physics 2021-10-14 S. L. Parnovsky