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Conference on "Variational and spectral methods in Quantum Field Theory"
Organizers: Volker Bach (Braunschweig), Maria J. Esteban (CNRS), Mathieu Lewin (CNRS), Eric Séré (Paris-Dauphine)


Detlev Buchholz (Göttingen, Germany): "New light on infrared problems: Sectors, statistics, spectrum and all that"
Tuesday 23 April 2013, 11:45 - 12:30
Amphi Hermite


Within the general setting of quantum field theory, a new approach to the analysis of the physical state space of a theory is presented which covers theories with long range forces, such as QED. Making use of the notion of charge class, which generalizes the concept of superselection sector, all infrared problems appearing in the usual interpretation of the theory are avoided. Based on this notion the genuine (non-infrared) sectors of a theory, the statistics of the corresponding states and their spectral properties can be determined and classified in a systematic manner. A key ingredient in this approach is the insight that inevitable experimental limitations provide a natural Lorentz invariant "infrared cutoff".