How well do lattice simulations reproduce the different aspects of the geometric Schwinger model

We compare continuum and lattice formulation of the geometric Schwinger Model on the torus. The lattice reproduces the $U(1)_A$ anomaly, related to non-trivial topological gauge configurations and zero modes.Comment: 3 pages, DESY 93-144, talk presented by H. Dilger at Lattice 9

Longest Paths in Circular Arc Graphs

As observed by Rautenbach and Sereni (arXiv:1302.5503) there is a gap in the proof of the theorem of Balister et al. (Longest paths in circular arc graphs, Combin. Probab. Comput., 13, No. 3, 311-317 (2004)), which states that the intersection of all longest paths in a connected circular arc graph is nonempty. In this paper we close this gap.Comment: 7 page

Elements of Environmental Decoherence

In this contribution I give a brief introduction to the essential concepts and mechanisms of decoherence by the environment. The emphasis will be not so much on technical details but rather on conceptual issues and the impact on the interpretation problem of quantum theory.Comment: Latex, 16 pages. To be published in the proceedings of the Bielefeld conference on ``Decoherence: Theoretical, Experimental, and Conceptual Problems", edited by P. Blanchard, D. Giulini, E. Joos, C. Kiefer, and I.-O. Stamatescu (Springer 1999