Doorway States and the Super-Radiant Mechanism

A new approach to physics of doorway states in nuclear reactions is developed. It is argued that the coupling of intrinsic states to the continuum through special doorway state(s) may create the situation similar to the optical super-radiance, when the segregation of broad (short-lived) resonances and trapped (long-lived) states occurs. Necessary conditions are discussed, along with applications to isobaric analog states, single-particle resonances, giant resonances, and fission through a double-humped barrier. This pattern can be observed in other mesoscopic systems as well