Related papers: Shear and Vorticity in an Accelerating Brans-Dicke…
A combined BCDE (Brans-Dicke and Einstein-Cartan) theory with lambda-term is developed through Raychaudhuri's equation, for inflationary scenario. It involves a variable cosmological constant, which decreases with time, jointly with energy…
We find a solution for exponential inflation in Brans-Dicke cosmology endowed with a cosmological term, which includes time-varying shear and vorticity. We find that the scalar field and the scale factor increase exponentialy while shear,…
Einstein-Cartan theory is an extension of the standard formulation of General Relativity characterized by a non-vanishing torsion. The latter is sourced by the matter fields via the spin tensor, and its effects are expected to be important…
We study chirality of the vorticity of the Universe within the Einstein-Cartan cosmology. The role of the spin of fermion species during the evolution of the Universe is studied by averaged spin densities and Einstein-Cartan equations. It…
The effects of non-Riemannian structures in Cosmology have been studied long ago and are still a relevant subject of investigation. In the seventies, it was discovered that singularity avoidance and early accelerated expansion can be…
Einstein-Cartan theory is an extension of the standard formulation of General Relativity where torsion (the antisymmetric part of the affine connection) is non-vanishing. Just as the space-time metric is sourced by the stress-energy tensor…
In addition to introducing matter injection through a scalar field determined by Pryce-Hoyle tensor, we also combine it with a BCDE (Brans-Dicke-Einstein-Cartan) theory with lambdaterm developed earlier by Berman(2008), for inflationary…
Einstein-aether theory is extended by allowing for spinning degrees of freedom of the aether. In addition to the acceleration, shear, expansion, and vorticity of the aether velocity field, a spin rotation describing the dynamics of a…
We consider Brans-Dicke theory with a self-interacting potential in Einstein conformal frame. We show that an accelerating expansion is possible in a spatially flat universe for large values of the Brans-Dicke parameter consistent with…
Inflation in the framework of Einstein-Cartan theory is revisited. Einstein-Cartan theory is a natural extension of the General Relativity, with non-vanishing torsion. The connection on Riemann-Cartan spacetime is only compatible with the…
We propose a simple scenario which explains why our Universe appears spatially flat, homogeneous and isotropic. We use the Einstein-Cartan-Kibble-Sciama (ECKS) theory of gravity which naturally extends general relativity to include the spin…
We show that in the Einstein-Cartan gravity it is possible to obtain a relation between Hubble's expansion and the global rotation (vorticity) of the Universe. Gravitational coupling can be reduced to dimensionless quantity of order unity,…
The evolution equation of cosmic density perturbation of a spin dominated universe in Einstein-Cartan gravity is obtained.Examples of inflationary cosmologies with spin are also given where we compute the density perturbations in terms of…
We show that the Einstein-Cartan-Sciama-Kibble theory of gravity with torsion not only extends general relativity to account for the intrinsic spin of matter, but it may also eliminate major problems in gravitational physics and answer…
We study a cosmological model based on the canonical Hamiltonian transformation theory. Using a linear-quadratic approach for the free gravitational De Donder-Weyl Hamiltonian $H_\mathrm{Gr}$, the model contains terms describing a…
Concordance cosmology points to a Universe of zero mean curvature, due to the inflation mechanism which occurred soon after the Big Bang, while along a relatively small number of lower redshift light paths where lensing events are observed,…
Cosmological inflation is discussed in the realm of Einstein-Cartan-Brans-Dicke (ECBD) gravity by constructing an effective inflaton potential and computing the number of e-folds.It is shown that spin-torsion density contributes to a…
We study gravity coupled to scalar and fermion fields in the Einstein-Cartan framework. We discuss the most general form of the action that contains terms of mass dimension not bigger than four, leaving out only contributions quadratic in…
The so-called Einstein-Aether theory is General Relativity coupled (at second derivative order) to a dynamical unit time-like vector field (the aether). It is a Lorentz-violating theory, and gained much attention in the recent years. In the…
We consider Brans-Dicke theory with a self-interacting potential in Einstein conformal frame. We introduce a class of solutions in which an accelerating expansion is possible in a spatially flat universe for positive and large values of the…