On the equivalence between topologically and non-topologically massive abelian gauge theories

We analyse the equivalence between topologically massive gauge theory (TMGT) and different formulations of non-topologically massive gauge theories (NTMGTs) in the canonical approach. The different NTMGTs studied are St\"uckelberg formulation of (A) a first order formulation involving one and two form fields, (B) Proca theory, and (C) massive Kalb-Ramond theory. We first quantise these reducible gauge systems by using the phase space extension procedure and using it, identify the phase space variables of NTMGTs which are equivalent to the canonical variables of TMGT and show that under this the Hamiltonian also get mapped. Interestingly it is found that the different NTMGTs are equivalent to different formulations of TMGTs which differ only by a total divergence term. We also provide covariant mappings between the fields in TMGT to NTMGTs at the level of correlation function.Comment: One reference added and a typos corrected. 15 pages, To appear in Mod. Phys. Lett.

Commentary CeNTech:nanotechnological research and application

The Centre for Nanotechnology (CeNTech), Münster, Germany, represents one of the first dedicated nanotechnology centres in Germany providing space and infrastructure for application, research and development in the area of nanotechnology. It offers an optimised environment for entrepreneurs to fur-ther develop their research ideas into marketable products as well as excellent conditions for application ori-ented research and further education. Three years after the opening of the CeNTech building most of the ex-pectations are fulfilled. The article describes the general aspects of the CeNTech concept and reviews its de-velopment in the first years

Differential geometry with a projection: Application to double field theory

In recent development of double field theory, as for the description of the massless sector of closed strings, the spacetime dimension is formally doubled, i.e. from D to D+D, and the T-duality is realized manifestly as a global O(D,D) rotation. In this paper, we conceive a differential geometry characterized by a O(D,D) symmetric projection, as the underlying mathematical structure of double field theory. We introduce a differential operator compatible with the projection, which, contracted with the projection, can be covariantized and may replace the ordinary derivatives in the generalized Lie derivative that generates the gauge symmetry of double field theory. We construct various gauge covariant tensors which include a scalar and a tensor carrying two O(D,D) vector indices.Comment: 1+22 pages, No figure; a previous result on 4-index tensor removed, presentation improve

An Equivalence Between Momentum and Charge in String Theory

It is shown that for a translationally invariant solution to string theory, spacetime duality interchanges the momentum in the symmetry direction and the axion charge per unit length. As one application, we show explicitly that charged black strings are equivalent to boosted (uncharged) black strings. The extremal black strings (which correspond to the field outside of a fundamental macroscopic string) are equivalent to plane fronted waves describing strings moving at the speed of light.Comment: 10 page

Two-Loop Beta Functions Without Feynman Diagrams

Starting from a consistency requirement between T-duality symmetry and renormalization group flows, the two-loop metric beta function is found for a d=2 bosonic sigma model on a generic, torsionless background. The result is obtained without Feynman diagram calculations, and represents further evidence that duality symmetry severely constrains renormalization flows.Comment: 4 pp., REVTeX. Added discussion on scheme (in)dependence; final version to appear in Phys. Rev. Let

Non-abelian T-duality, Ramond Fields and Coset Geometries

We extend previous work on non-abelian T-duality in the presence of Ramond fluxes to cases in which the duality group acts with isotropy such as in backgrounds containing coset spaces. In the process we generate new supergravity solutions related to D-brane configurations and to standard supergravity compactifications.Comment: 35 pages, Late

Two-Vierbein Formalism for String-Inspired Axionic Gravity

Using independent left and right vierbeins to describe graviton plus axion as suggested by string mechanics, O(d,d) duality can be realized linearly.Comment: 14 pg., (uuencoded dvi file; fixed uuencoding so file is unprotected) ITP-SB-93-

The non-uniform, dynamic atmosphere of Betelgeuse observed at mid-infrared wavelengths

We present an interferometric study of the continuum surface of the red supergiant star Betelgeuse at 11.15 microns wavelength, using data obtained with the Berkeley Infrared Spatial Interferometer each year between 2006 and 2010. These data allow an investigation of an optically thick layer within 1.4 stellar radii of the photosphere. The layer has an optical depth of ~1 at 11.15 microns, and varies in temperature between 1900 K and 2800 K and in outer radius between 1.16 and 1.36 stellar radii. Electron-hydrogen atom collisions contribute significantly to the opacity of the layer. The layer has a non-uniform intensity distribution that changes between observing epochs. These results indicate that large-scale surface convective activity strongly influences the dynamics of the inner atmosphere of Betelgeuse, and mass-loss processes.Comment: 13 pages, 5 figures, in press (ApJ

Supersymmetric String Waves

We present plane-wave-type solutions of the lowest order superstring effective action which have unbroken space-time supersymmetries. They describe dilaton, axion and gauge fields in a stringy generalization of the Brinkmann metric. Some conspiracy between the metric and the axion field is required. We show that there exists a special class of these solutions, for which $\alpha^\prime$ stringy corrections to the effective on-shell action, to the equations of motion (and therefore to the solutions themselves), and to the supersymmetry transformations vanish. We call these solutions supersymmetric string waves (SSW).Comment: 19 pages, LaTeX, SU-ITP-92-30 and UG-10/9

Nonsingular 2-D Black Holes and Classical String Backgrounds

We study a string-inspired classical 2-D effective field theory with {\it nonsingular} black holes as well as Witten's black hole among its static solutions. By a dimensional reduction, the static solutions are related to the $(SL(2,R)_{k}\otimes U(1))/U(1)$ coset model, or more precisely its $O\bigl((\alpha')^{0}\bigr)$ approximation known as the 3-D charged black string. The 2-D effective action possesses a propagating degree of freedom, and the dynamics are highly nontrivial. A collapsing shell is shown to bounce into another universe without creating a curvature singularity on its path, and the potential instability of the Cauchy horizon is found to be irrelevent in that some of the infalling observers never approach the Cauchy horizon. Finally a $SL(2,R)_{k}/U(1)$ nonperturbative coset metric, found and advocated by R. Dijkgraaf et.al., is shown to be nonsingular and to coincide with one of the charged spacetimes found above. Implications of all these geometries are discussed in connection with black hole evaporation.Comment: 30 pages with 2 figures, harvmac, CALT-68-1852 (Discussions on the gravitational collapse of thin shells in a charged spacetime are clarified. Two extra references.