Tutorial on Scale and Conformal Symmetries in Diverse Dimensions

We review the relation between scale and conformal symmetries in various models and dimensions. We present a dimensional reduction from relativistic to non-relativistic conformal dynamics.Comment: Addendum added that includes author S.-H. Ho; Sodano Fest, Perugia, Italy, January 201

Covariant Coordinate Transformations on Noncommutative Space

We show how to define gauge-covariant coordinate transformations on a noncommuting space. The construction uses the Seiberg-Witten equation and generalizes similar results for commuting coordinates.Comment: 11 pages, LaTeX; email correspondence to [email protected]

Lorentz Violation in a Diffeomorphism-Invariant Theory

In a diffeomorphism invariant theory, symmetry breaking may be a mask for coordinate choice.Comment: 8 pages, no figures. Submitted to the CPT'07 Proceeding

4-Dimensional Einstein Theory Extended by a 3-Dimensional Chern-Simons Term

When 4-dimensional general relativity is extended by a 3-dimensional gravitational Chern-Simons term an apparent violation of diffeormorphism invariance is extinguished by the dynamical equations of motion for the modified theory. The physical predictions of this recently proposed model show little evidence of symmetry breaking, but require the vanishing of the Pontryagin density.Comment: 11 pages, 0 figure