Frank Gronwald

Metric-Affine Gauge Theory of Gravity: I. Fundamental Structure and Field Equations

We give a self-contained introduction into the metric–affine gauge theory of gravity. Starting from the equivalence of reference frames, the prototype of a gauge theory is presented and illustrated by the example of Yang–Mills theory. Along the same lines we perform a gauging of the affine group and establish the geometry of metric–affine gravity. The results are put into the dynamical framework of a classical field theory. We derive subcases of metric-affine gravity by restricting the affine group to some of its subgroups. The important subcase of general relativity as a gauge theory of tranlations is explained in detail.

A Brief Guide to Variations in Teleparallel Gauge Theories of Gravity and the Kaniel-Itin Model

AbstractRecently Kaniel and Itin proposed a gravitational model with the wave type equation

Calculation of mutual antenna coupling within rectangular enclosures

\left[ { + \lambda \left( x \right)} \right]\vartheta ^\alpha = 0

On detecting the gravitomagnetic field of the Earth by means of orbiting clocks

as vacuum field equation, where

BRST antifield treatment of metric-affine gravity

\vartheta ^\alpha

A Measurement Setup for Quantification of Electromagnetic Interference in Metallic Casings

denotes the coframe of spacetime. They found that the viable Yilmaz-Rosen metric is an exact solution of the tracefree part of their field equation. This model belongs to the teleparallelism class of gravitational gauge theories. Of decisive importance for the evaluation of the Kaniel-Itin model is the question whether the variation of the coframe commutes with the Hodge star. We find a master formula for this commutator and rectify some corresponding mistakes in the literature. Then we turn to a detailed discussion of the Kaniel-Itin model.