ar X iv : 0 70 9 . 01 76 v 1 [ m at h . D G ] 3 S ep 2 00 7 REPRESENTATIONS OF ORBIFOLD GROUPOIDS

ar X iv : 0 70 9 . 01 76 v 2 [ m at h . D G ] 1 1 O ct 2 00 7 REPRESENTATIONS OF ORBIFOLD GROUPOIDS

Orbifold groupoids have been recently widely used to represent both effective and ineffective orbifolds. We show that every orbifold group-oid can be faithfully represented on a continuous family of finite dimensional Hilbert spaces. As a consequence we obtain the result that every orbifold groupoid is Morita equivalent to the translation groupoid of an almost free action of a proper bundle of ...

ar X iv : h ep - l at / 0 01 20 10 v 1 7 D ec 2 00 0 1 The Vacuum Polarization : Power Corrections beyond OPE ? ∗

X iv :h ep -l at /0 01 20 10 v1 7 D ec 2 00 0 1 The Vacuum Polarization: Power Corrections beyond OPE ? ∗ M. Göckeler, R. Horsley, W. Kürzinger, V. Linke, D. Pleiter, P. E. L. Rakow and G. Schierholz Institut für Theoretische Physik, Universität Regensburg, D-93040 Regensburg, Germany Deutsches Elektronen-Synchrotron DESY & NIC, D-15735 Zeuthen, Germany Institut für Physik, Humboldt-Universität...

ar X iv : 0 80 9 . 01 74 v 1 [ m at h - ph ] 1 S ep 2 00 8 Heisenberg relations in the general case

The Heisenberg relations are derived in a quite general setting when the field transformations are induced by three representations of a given group. They are considered also in the fibre bundle approach. The results are illustrated in a case of transformations induced by the Poincaré group.

ar X iv : 0 70 9 . 05 64 v 1 [ m at h . C O ] 5 S ep 2 00 7 3 - bounded Property in a Triangle - free Distance - regular Graph ∗

Let Γ denote a distance-regular graph with classical parameters (D, b, α, β) and D ≥ 3. Assume the intersection numbers a1 = 0 and a2 6= 0. We show Γ is 3-bounded in the sense of the article [D-bounded distance-regular graphs, European Journal of Combinatorics(1997)18, 211-229].

ar X iv : h ep - p h / 05 12 21 6 v 2 1 7 D ec 2 00 5 QUANTIZATION AND HIGH ENERGY UNITARITY IN ORBIFOLD THEORIES