Interfering Doorway States and Giant Resonances I: Resonance Spectrum and Multipole Strengths

Abstract
Using a phenomenological schematic model of multipole giant resonances we consider the effects of overlapping of their doorway components. The conccpt of the partial widths of a giant resonance becomes ambiguous when the escape widths get comparable with the spacings between the components. In such a case, the partial widths determined in terms of the K- and S-matrices differ from each othcr. The mixing of the doorway components due to the interaction via the common decay channels influences significantly their multipole strengths, widths and positions in energy.