GAMOW VECTORS FOR DEGENERATE SCATTERING RESONANCES

In this paper we construct Gamow vectors for resonances given by poles of the analytic continuation of the S matrix of any finite order. We study their modes of decay (or growth). We obtain Jordan block structu res for the extended Hamiltonians and evolution operators on the subsp aces spanned by these Gamow vectors. We perform this study within the context of the rigged Hilbert space extension of quantum theory. We co nstruct an explicit Friedrichs model with a double pole resonance to i llustrate the general formulation. (C) 1998 American Institute of Phys ics.