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Gerbes, (twisted) K-theory, and the supersymmetric WZW model

Jouko Mickelsson
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Abstract

The aim of this talk is to explain how symmetry breaking in a quantum field theory problem leads to a study of projective bundles, Dixmier-Douady classes, and associated gerbes. A gerbe manifests itself in different equivalent ways. Besides the cohomological description as a DD class, it can be defined in terms of a family of local line bundles or as a prolongation problem for an (infinite-dimensional) principal bundle, with the fiber consisting of (a subgroup of) projective unitaries in a Hilbert space. The prolongation aspect is directly related to the appearance of central extensions of (broken) symmetry groups. We also discuss the construction of twisted K-theory classes by families of supercharges for the supersymmetric Wess-Zumino-Witten model.

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Jouko Mickelsson. 2002-12-06. Gerbes, (twisted) K-theory, and the supersymmetric WZW model. https://arxiv.org/abs/hep-th/0206139

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