Yu. N. Obukhov

Lessons of spin and torsion: Reply to "Consistent coupling to Dirac fields in teleparallelism"

In reply to the criticism made by Mielke in the preceding Comment on our recent paper, we once again explicitly demonstrate the inconsistency of the coupling of a Dirac field to gravitation in the teleparallel equivalent of general relativity. Moreover, we stress that the mentioned inconsistency is generic for all sources with spin and is by no means restricted to the Dirac field. In this sense the SL(4,R)-covariant generalization of the spinor fields in the teleparallel gravity theory is irrelevant to the inconsistency problem.

An Exact solution of the metric affine gauge theory with dilation, shear, and spin charges

Abstract The spacetime of the metric-affine gauge theory of gravity (MAG) encompasses nonmetricity Qαβ and torsion Tα as post-Riemannian structures. The sources of MAG are the conserved currents of energy-momentum and dilation ⊕ shear ⊕ spin. We present an exact static spherically symmetric vacuum solution of the theory describing the exterior of a lump of matter carrying mass and dilation ⊕ shear ⊕ spin charges.

An axially symmetric solution of metric-affine gravity

We present an exact stationary axially symmetric vacuum solution of metric-affine gravity (MAG) which generalizes the recently reported spherically symmetric solution; besides the metric, it carries nonmetricity and torsion as post-Riemannian geometrical structures. The parameters of the solution are interpreted as mass and angular momentum and as dilation, shear and spin charges.

Teleparallel origin of the Fierz picture for spin-2 particle

A new approach to the description of a spin-2 particle in flat and curved spacetime is developed on the basis of the teleparallel gravity theory. We show that such an approach is in fact a true and natural framework for the Fierz representation proposed recently by Novello and Neves. More specifically, we demonstrate how the teleparallel theory fixes uniquely the structure of the Fierz tensor, discover the transparent origin of the gauge symmetry of the spin-2 model, and derive the linearized Einstein operator from the fundamental identity of the teleparallel gravity. In order to cope with the consistency problem on the curved spacetime, similarly to the usual Riemannian approach, one needs to include the nonminimal ~torsion dependent! coupling terms.

Can cosmic rotation explain an apparently periodic universe

We demonstrate a possible explanation of the observed periodicity of the large-scale distribution of galaxies as an effect of the global rotation of the universe.

Gödel type solution in teleparallel gravity

The stationary cosmological model without closed timelike curves of Godel type is obtained for the ideal dust matter source within the framework of the teleparallel gravity. For a specific choice of the teleparallel gravity parameters, this solution reproduces the causality violating stationary Godel solution in general relativity, in accordance with the teleparallel equivalent of general relativity. The relation between the axial-vector torsion and the cosmic vorticity is clarified.

Reduction of the dirac equation and its connection with the Ivanenko-Landau-Kähler equation

The theory of spinors isconsidered in the framework of the formalism of inhomogeneous differential forms. The possibility of describing fermions by means of the Ivanenko-Landau-Kählerequation and its connection with the standard Dirac equation are investigated.

Gauge fields and space-time geometry

Mappings between the SU (2) Yang-Mills gauge theory and the gauge gravity theory are discussed. The global aspects are considered in the framework of the fiber-bundle technique, and three different local constructions (depending on the existence of a fixed background metric) are described in detail.

Motion of spin in the gravitational field of a rotating body

A relativistic equation describing the motion of a classical spin in curved spacetimes is obtained. Classical and quantum equations of motion of spin in the gravitational field of a rotating body are derived.

Experimental bounds on parameters of spin-spin interaction in gauge theory of gravitation

The contribution of the pseudovector component of the torsion for the hyperfine splitting of the hydrogen atom is considered. The calculations are made in the framework of a Poincaré gauge theory of gravitation with the most general Lagrangian quadratic in the curvature and torsion and containing a term of Hilbert-Einstein type. Some estimates of the model are obtained.