12 research outputs found
Anisotropic cosmological models with spinor and scalar fields and viscous fluid in presence of a term: qualitative solutions
The study of a self-consistent system of interacting spinor and scalar fields
within the scope of a Bianchi type I (BI) gravitational field in presence of a
viscous fluid and term has been carried out. The system of equations
defining the evolution of the volume scale of BI universe, energy density and
corresponding Hubble constant has been derived. The system in question has been
thoroughly studied qualitatively. Corresponding solutions are graphically
illustrated. The system in question is also studied from the view point of blow
up. It has been shown that the blow up takes place only in presence of
viscosity.Comment: 18 pages, 14 figures, 12 Tables, section "Basic equations" has been
rewritte
Bel-Robinson tensor and dominant energy property in the Bianchi type I Universe
Within the framework of Bianchi type-I space-time we study the Bel-Robinson
tensor and its impact on the evolution of the Universe. We use different
definitions of the Bel-Robinson tensor existing in the literature and compare
the results. Finally we investigate the so called "dominant super-energy
property" for the Bel-Robinson tensor as a generalization of the usual dominant
energy condition for energy momentum tensors.
Keywords: Bianchi type I model, super-energy tensors
Pacs: 03.65.Pm and 04.20.HaComment: 15 pages, revised version, no figure
Bianchi type-I string cosmological model in the presence of a magnetic field: classical versus loop quantum cosmology approaches
A Bianchi type-I cosmological model in the presence of a magnetic flux along
a cosmological string is considered. The first objective of this study is to
investigate Einstein equations using a tractable assumption usually accepted in
the literature. Quantum effects of the present cosmological model are examined
in the framework of loop quantum cosmology. Finally we draw a parallel between
the classical and quantum approaches.Comment: 14 pages, 8 figure