Classification of resonances and pairing effects on $NA$-scattering within the HFB framework

Phys. Rev. C 104, 034606 (2021) We analyze the properties of the scattering solutions obtained as the pole of the S- and K-matrix with the help of the Jost function framework and the Strum-Liouville theory within the Hartree-Fock-Bogoliubov(HFB) framework, and clarify the scattering solutions which can be defined as the physical state. We found that there are three types of the resonances; "{\it shape resonance}", "{\it particle-type}" and "{\it hole-type quasiparticle resonances}", and another two types of solutions are given as the independent S-matrix and K-matrix poles. The shape resonance is formed by the Hartree-Fock(HF) mean field potential, is not affected by the pairing correlation so much. The particle-type and hole-type quasiparticle resonances originate from the particle and hole states by the configuration mixing effect by pairing. All of resonance are represented by the S-matrix pole which has the corresponding K-matrix pole. Two other types of solutions are given by the independent S-matrix and K-matrix poles. These poles are formed by the HF mean field potential. The effect of pairing for the independent S-matrix pole is small, but the one for the independent K-matrix pole has the remarkable effect. The independent K-matrix pole destroys the quasiparticle resonance as it approaches to the resonance by the pairing effect. The wave function of all resonances have the characteristic structure of the metastable property. However, the metastable structure of the wave function of the quasiparticle resonance can be broken by the independent standing wave solution or the Fano effect.