PARTICLE-VIBRATION COUPLING IN A BASIS WITH RESONANT STATES

Neutron and proton bound states and Gamow resonances (Berggren representation) are used as single-particle states to calculate random-phase approximation (RPA) particle-hole-multipole excitations in Pb-208 and vertex functions for the coupling between particles and multipole vibrations. Escape widths, corresponding to low-lying one-proton states in the neighborhood of the Z = 82 shell, are calculated in the framework of the standard particle-vibration coupling model. It is shown that the inclusion of Gamow resonances in the single-particle basis and in the RPA wave functions does not affect the dominant one-particle character of low-lying states of the renormalized spectrum corresponding to the odd-even system, as predicted by the particle-vibration coupling model. This result shows that the Berggren representation is suitable to deal with the particle-vibration coupling mechanism and that it can be a lied to the study of high-lying single-particle states as well.