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We introduce a cosmological model in the framework of Generalised Massive Gravity. This theory is an extension of non-linear massive gravity with a broken translation symmetry in the St\"uckelberg space. In a recent work, we showed the…

General Relativity and Quantum Cosmology · Physics 2020-11-25 Michael Kenna-Allison , A. Emir Gumrukcuoglu , Kazuya Koyama

The observed late-time acceleration of the cosmic expansion constitutes a fundamental problem in modern theoretical physics and cosmology. In an attempt to weight the validity of a large number of dark energy models, I use the recent…

Cosmology and Nongalactic Astrophysics · Physics 2010-01-21 Spyros Basilakos

An accelerated universe should naturally have a vacuum energy density determined by its dynamical curvature. The cosmological constant is most likely a temporary description of a dynamical variable that has been drastically evolving from…

General Relativity and Quantum Cosmology · Physics 2015-10-28 Joan Sola

We analyse the cosmological evolution of a generalised axion-like field that drives the late-time acceleration of the Universe. This model can exhibit tracking behaviour, which alleviates the coincidence problem. The cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-29 Carlos G. Boiza , Mariam Bouhmadi-López

The acceleration of the expansion of the universe, ascribed to a dark energy, is one of the most intriguing discoveries in science. In addition to precise, systematics controlled data, clear, robust interpretation of the observations is…

Astrophysics · Physics 2009-11-10 Eric V. Linder

We investigate the possibility of replacing the cosmological constant with gradual condensation of a scalar field produced during the decay of a superheavy dark matter. The advantage of this class of models to the ordinary quintessence is…

Astrophysics · Physics 2009-11-10 Houri Ziaeepour

Recent astronomical observations of distant supernovae light-curves suggest that the expansion of the universe has recently begun to accelerate. Acceleration is created by an anti-gravitational repulsive stress, like that produced by a…

Astrophysics · Physics 2009-10-31 John Barrow , Rachel Bean , Joao Magueijo

While general relativity ties together the cosmic expansion history and growth history of large scale structure, beyond the standard model these can have independent behaviors. We derive expressions for cosmologies with identical growth…

Cosmology and Nongalactic Astrophysics · Physics 2022-04-21 Eric V. Linder

As discussed in a number of recent papers, cosmological stasis is a phenomenon wherein the abundances of multiple cosmological energy components with different equations of state remain constant for an extended period despite the expansion…

Cosmology and Nongalactic Astrophysics · Physics 2025-03-27 Keith R. Dienes , Lucien Heurtier , Daniel Hoover , Fei Huang , Anna Paulsen , Brooks Thomas

We explore an extension of the symmetric teleparallel gravity denoted the $f(Q)$ theory, by considering a function of the nonmetricity invariant $Q$ as the gravitational Lagrangian. Some interesting properties could be found in the $f(Q)$…

General Relativity and Quantum Cosmology · Physics 2019-06-24 Jianbo Lu , Xin Zhao , Guoying Chee

We have critically compared different approaches to the cosmological constant problem, which is at the edge of elementary particle physics and cosmology. This problem is deeply connected with the difficulties formulating a theory of quantum…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Stefan Nobbenhuis

Cosmology is investigated within a new, scalar theory of gravitation, which is a preferred-frame bimetric theory with flat background metric. Before coming to cosmology, the motivation for an " ether theory " is exposed at length; the…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Mayeul Arminjon

The implications of string theory for understanding the dimension of uncompactified spacetime are investigated. Using recent ideas in string cosmology, a new model is proposed to explain why three spatial dimensions grew large. Unlike the…

High Energy Physics - Theory · Physics 2010-11-01 Gerald B. Cleaver , Philip J. Rosenthal

We look for cosmologies with a scalar field (dark energy without cosmological constant), which mimic the standard $\Lambda CDM$ cosmological model yielding exactly the same large-scale geometry described by the evolution of the Hubble…

Astrophysics · Physics 2015-05-13 V. I. Zhdanov , G. Ivashchenko

Observations provide increasingly strong evidence that the universe is accelerating. This revolutionary advance in cosmological observations confronts theoretical cosmology with a tremendous challenge, which it has so far failed to meet.…

Astrophysics · Physics 2008-11-26 Ruth Durrer , Roy Maartens

Old and new puzzles of cosmology are reexamined from the point of view of quantum theory of the universe developed here. It is shown that in proposed approach the difficulties of the standard cosmology do not arise. The theory predicts the…

General Relativity and Quantum Cosmology · Physics 2007-05-23 V. E. Kuzmichev , V. V. Kuzmichev

The cosmographic technique is a powerful model-independent tool for distinguishing between competing cosmological scenarios. The key strengths and weaknesses of standard cosmography are discussed in view of healing the convergence problem…

Cosmology and Nongalactic Astrophysics · Physics 2022-12-01 Salvatore Capozziello , Rocco D'Agostino

We have fossil evidence from the thermal background radiation that our universe expanded from a considerably hotter denser state. We have a well defined and testable description of the expansion, the relativistic Friedmann-Lemaitre model.…

Astrophysics · Physics 2009-10-31 P. J. E. Peebles

We develop a cosmological theory in which the evolution of the universe is controlled by the cosmological constant and dominated by the associated vacuum energy. The universe starts as a classical de Sitter space with an infinite effective…

General Physics · Physics 2023-03-21 J. M. Greben

Cosmic structures at large scales represent the earliest and most extended form of matter condensation. In this lecture we review the application of the methods and concepts of modern statistical physics to these structures. This leads to a…

Astrophysics · Physics 2017-08-23 Luciano Pietronero , Francesco Sylos Labini