Where:	Besprechungsraum N24, 1st floor, Nebengebäude, Mathematisches Institut.
When:	Wednesdays, 13:00 - 14:00

Programme:

Nov 12	André Fischer, Hannover:  Quantum Field Theories on Noncommutative Minkowski Spacetime. Change of location The talk will take place in the Schlauch (next to Sitzungszimmer) in the main building. We apologize for the inconvenience! Recently the renormalization of noncommutative quantum field theories (NCQFT) has undergone enormous progress. Several models defined on Euclidean space obeying LS-duality have been proven renormalizable. However, in contrast to the commutative case, the perturbative dynamics of noncommutative theories in Minkowski space cannot be simply obtained via a Wick rotation of their Euclidean counterparts. Accordingly there is little known about noncommutative field theories with Minkowski signature. In this talk, I will show how to continue euclidean NCQFT to Minkowski spacetime by constructing a suitable (resonance) expansion of charged scalar fields. This yields an effective description of the field theories in terms of two-matrix models and hence reveals the unexpected feature of Minkowskian theories of having an additional matrix degree of freedom ensuring unitarity and \bf{CT}-invariance. As a byproduct, this analysis provides a rigorous mathematical proof of the "Electric-Magnetic Duality" known in the treatment of QED effective actions.