We review and then combine two aspects of the theory of bundle gerbes. The first concerns lifting bundle gerbes and connections on those, developed by Murray and Gomi. Lifting gerbes represent obstructions against extending the structure group of a principal bundle. The second is the transgression of gerbes to loop spaces, initiated by Brylinski and McLaughlin and with recent contributions of the author. Combining these two aspects, we obtain a new formulation of lifting problems in terms of geometry on the loop space. Most prominently, our formulation explains the relation between (complex) spin structures on a Riemannian manifold and orientations of its loop space.
- Pub Date:
- July 2010
- Mathematics - Differential Geometry;
- 19 pages. v2 is the published version and comes with a few minor changes. v3 corrects a sign mistake in Lemma 3.6, forcing a change of sign in the main theorem