Ballesteros, Miguel; Deckert, DirkAndre; Haenle, Felix
(2019):
Relation Between the Resonance and the Scattering Matrix in the Massless SpinBoson Model.
In: Communications in Mathematical Physics, Vol. 370, No. 1: pp. 249290

Full text not available from 'Open Access LMU'.
Abstract
We establish the precise relation between the integral kernel of the scattering matrix and the resonance in the massless SpinBoson model which describes the interaction of a twolevel quantum system with a secondquantized scalar field. For this purpose, we derive an explicit formula for the twobody scattering matrix. We impose an ultraviolet cutoff and assume a slightly less singular behavior of the boson form factor of the relativistic scalar field but no infrared cutoff. The purpose of this work is to bring together scattering and resonance theory and arrive at a similar result as provided by Simon (Ann Math Sect Ser 97(2):247274, 1973), where it was shown that the singularities of the meromorphic continuation of the integral kernel of the scattering matrix are located precisely at the resonance energies. The corresponding problem has been open in quantum field theory ever since. To the best of our knowledge, the presented formula provides the first rigorous connection between resonance and scattering theory in the sense of (Simon 1973) in a model of quantum field theory.