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The conditions under which cosmologies driven by time varying cosmological terms can be described by a scalar field coupled to a perfect fluid are discussed. An algorithm to reconstruct potentials dynamically and thermodynamically analogue…

Astrophysics · Physics 2009-11-07 J. M. F. Maia , J. A. S. Lima

We investigate the cosmological dynamics in a spatially flat Friedmann--Lema\^{\i}tre--Robertson--Walker geometry in scalar-tensor and scalar-torsion theories where the nonminimally coupled scalar field is a complex field. We derive the…

General Relativity and Quantum Cosmology · Physics 2022-11-23 Andronikos Paliathanasis

In this paper we consider FRW cosmology in modified non-local gravity. The stability analysis shows that there is only one stable critical point for the model and the universe undergoes a quintessence dominated era.

General Relativity and Quantum Cosmology · Physics 2011-06-09 H. Farajollahi , F. Milani

We develop a framework to study the phase space of a system consisting of a scalar field rolling down an arbitrary potential with varying slope and a background fluid, in a cosmological setting. We give analytical approximate solutions of…

Astrophysics · Physics 2008-11-26 S. C. C. Ng , N. J. Nunes , F. Rosati

We discuss the issue of unitarity in particular quantum cosmological models with scalar field. The time variable is recovered, in this context, by using the Schutz's formalism for a radiative fluid. Two cases are considered: a phantom…

General Relativity and Quantum Cosmology · Physics 2015-09-23 C. R. Almeida , A. B. Batista , J. C. Fabris , P. R. L. V. Moniz

We explore the dynamical behaviour of cosmological models involving a scalar field (with an exponential potential and a canonical kinetic term) and a matter fluid with spatial curvature included in the equations of motion. Using…

General Relativity and Quantum Cosmology · Physics 2016-10-13 Mateja Gosenca , Peter Coles

We investigate the evolution of a spatially flat Friedmann-Robertson-Walker (FRW) universe in the framework of scalar non-metricity theory of gravity. In the model, we consider dark matter (DM) and dark energy (DE) described by the scalar…

General Relativity and Quantum Cosmology · Physics 2025-08-05 Bikash Chandra Roy , Bikash Chandra Paul

In the present work, the flat FLRW Universe has been modelled with cosmic matter in the form of diffusive barotropic fluid. The diffusive fluid undergoes dissipation due to diffusion mechanism in the form of cosmological scalar field. From…

General Relativity and Quantum Cosmology · Physics 2023-02-22 Subhayan Maity , Subenoy Chakraborty

We study FRW cosmology for a double scalar - tensor theory of gravity where two scalar fields are nonminimally coupled to the geometry. In a framework to study stability and attractor solutions of the model in the phase space, we constraint…

General Physics · Physics 2015-06-03 H. Farajollahi , A. Shahabi , A. Salehi

The present work deals with a FLRW cosmological model with spatial curvature and minimally coupled scalar field as the matter content. The curvature term behaves as a perfect fluid with the equation of state parameter w_K = -1/3 Using…

General Relativity and Quantum Cosmology · Physics 2024-07-09 Soumya Chakraborty , Sudip Mishra , Subenoy Chakraborty

The background dynamical evolution of a universe filled with matter and a cosmological scalar field is analyzed employing dynamical system techniques. After the phenomenology of a canonical scalar field with exponential potential is…

General Relativity and Quantum Cosmology · Physics 2014-04-23 Nicola Tamanini

The behaviour of the flat anisotropic model of the Universe with a scalar field is explored within the framework of quantum cosmology. The principal moment of the account of an anisotropy is the presence either negative potential barrier or…

General Relativity and Quantum Cosmology · Physics 2015-06-25 V. N. Folomeev , V. Ts. Gurovich

We consider cosmological models with an arbitrary number of scalar fields nonminimally coupled to gravity and construct new integrable cosmological models. In the constructed models, the Ricci scalar is an integral of motion irrespectively…

General Relativity and Quantum Cosmology · Physics 2025-05-23 V. R. Ivanov , S. Yu. Vernov

In this paper, we consider spatially flat FLRW cosmological models in two contexts in an attempt to derive a set of conditions that characterize when such models exhibit oscillatory behaviour. In the first case, we consider a spatially flat…

General Relativity and Quantum Cosmology · Physics 2017-06-12 Ikjyot Singh Kohli

Cosmological models often contain scalar fields, which can acquire global nonzero expectation values that change with the comoving time. Among the possible consequences of these scalar-field backgrounds, an accelerated cosmological…

High Energy Physics - Phenomenology · Physics 2017-08-23 Ralf Lehnert

We study the Fock quantization of scalar fields in (generically) time dependent scenarios, focusing on the case in which the field propagation occurs in --either a background or effective-- spacetime with spatial sections of flat compact…

General Relativity and Quantum Cosmology · Physics 2012-11-26 Laura Castelló Gomar , Jerónimo Cortez , Daniel Martín-de Blas , Guillermo A. Mena Marugán , José M. Velhinho

A detailed comparative qualitative analysis and numerical simulation of evolution of the cosmological models based on classical and phantom scalar fields with self-action was performed. The phase portraits of the dynamic systems of…

General Relativity and Quantum Cosmology · Physics 2018-08-15 Yurii Ignat'ev , Alexander Agathonov , Irina Kokh

We study the dynamical evolution of cosmological models with the Robertson-Walker symmetry with a scalar field non-minimally coupled to gravity and barotropic matter. For this aim we use dynamical system methods. We have found a type of…

Cosmology and Nongalactic Astrophysics · Physics 2010-12-02 Orest Hrycyna , Marek Szydlowski , Adam Krawiec

We study evolution of cosmological models filled with the scalar field and barotropic matter. We consider the scalar field minimally and non-minimally coupled to gravity. We demonstrated the growth of degree of complexity of evolutional…

Cosmology and Nongalactic Astrophysics · Physics 2012-12-20 Orest Hrycyna , Marek Szydlowski

We review a cosmology in which particles are fluctuationally created from a background Zero Point Field. This cosmology is consistent with recent observations of an ever expanding and accelerating universe, as also the recently confirmed…

General Physics · Physics 2015-06-26 B. G. Sidharth