13/03/2013, 11:30 — 12:30 — Room P3.10, Mathematics Building
John Huerta, Instituto Superior Técnico
Anomalies IIIWe continue examining Gawedzki and Reis's paper:
WZW branes and gerbes, http://arxiv.org/abs/hep-th/0205233
We define a gerbe, and show gerbes can be "transgressed" to give line bundles over loop space. Trivial gerbes give trivial bundles on loop space, whose sections are thus mere functions. Any compact, simply connected Lie group comes with a god-given gerbe whose curvature is the canonical invariant 3-form. Restricting this gerbe to certain submanifolds, we get trivial gerbes who thus transgress to trivial line bundles, "cancelling" the anomaly of a nontrivial line bundle.