Gerbes and (unoriented) WZW-Models

Konrad Waldorf
  Department of Mathematics, University of Hamburg, Germany

Gerbes (with connective structure) provide a natural language for the lagrangian description of oriented Wess-Zumino-Witten models. Gerbe modules - certain additional structure - admit to incorporate D-branes.

In the talk I will review these constructions, and then introduce a new additional structure on a gerbe, called a Jandl structure. Gerbes with Jandl structure provide a candidate for the Wess-Zumino term on unoriented worldsheets. The ansatz reproduces some results known from the algebraic approach to unoriented WZW models.