Seminarium Teorii Względności i Grawitacji

This talk is devoted to the geometric approach to supergravity and applications in the framework of loop quantum gravity (LQG). Among other things, this approach leads to a reformulation of the theory in which (part of) supersymmetry manifests itself in terms of a gauge symmetry. Using the interpretation of supergravity in terms of a super Cartan geometry, we will derive the Holst variant of the MacDowell-Mansouri action for N-extended AdS supergravity in D=4 for arbitrary values of the Barbero-Immirzi parameter - a free parameter of the theory. We will show that these actions provide unique boundary terms that ensure local supersymmetry invariance at boundaries. The chiral case is special: The action is invariant under an enlarged gauge symmetry, and the boundary theory is a super Chern-Simons theory. The action also implies boundary conditions that link the super electric flux through, and the super curvature on, the boundary. Making use of the enlarged gauge symmetry, we propose a quantization of the theory generalizing standard tools of LQG. Finally, we will give an outlook on applications of these results in the context of supersymmetric black holes and quantum cosmology. There, the enhanced gauge symmetry proves to be a promising tool which in the future may shed a lot of insights on how to relate results from LQG and superstring theory. The seminar is also broadcasted in room 1.40