论文部分内容阅读
I shall give an interpretation of the gauge anomaly of the two-dimensional multi-phase sigma model in terms of an obstruction to the existence of a topological defect network implementing the action of the gauge group in the gauged sigma model.A link to the construction of principal bundles with a structural (action) groupoid over the world-sheet will be established,and a relation to the Courant-algebroidal interpretation of the small gauge anomaly will be discussed.