RESUMO
We study the effect of mass on geometric descriptions of gauge field theories. In an approach in which the massless theory resembles general relativity, the introduction of the mass entails non-zero torsion and the generalization to Einstein-Cartan-Sciama-Kibble theories. The relationships to pure torsion formulations (teleparallel gravity) and to higher gauge theories are also discussed.
RESUMO
In this paper models for the relation of specular density to incident (x-ray) intensity with uncertainties are applied to experimental data, indicating methods for the correction of additional effects. Linearization and error calculations are simplified by double linear interpolation, and the effect of this is quantified. Relative first-order intensities are determined directly. Secondary linearization or calculation for higher-order lines gives correction factors that yield absolute and relative higher-order intensity ratios. The effects of energy and angle on linearization are included. Densitometry uncertainty is estimated and quantified.
