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An excited eigenvalue of an atom is believed to be unstable and turn into a resonance under a perturbation. In this talk the precise definition of such resonances is given and their existence and construction is outlined in case the atom is minimally coupled to the quantized radiation field. This model is infrared singular and notoriously difficult to treat. We review Sigal’s recent construction of resonances based on the “Feshbach map” and present a novel, alternative construction based on “Pizzo’s method”.

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Volker Bach, Technische Universität Braunschweig
Seminarraum Theoretische Physik
Contact: not specified