Threshold states in schematic models

Abstract

The possibility of strength decoupling from the giant dipole resonance is shown in the Brown-Bolsterli and Goswami-Pal schematic models, modified to incorporate the features of the threshold states, and in continuum shell-model calculations. Two essential features are considered: the threshold states have lower particle-hole energy than the other normal states and the coupling between the threshold and the normal states via the residual interaction is weaker than between states of identical type.