Particle-vibration coupling for giant resonances beyond the diagonal approximation

TL;DR

This paper develops a self-consistent particle-vibration coupling model that goes beyond the diagonal approximation, improving the description of giant resonances in 16O by including interactions between doorway states.

Contribution

It introduces a PVC model without the diagonal approximation, accounting for interactions between particle-hole pairs within doorway states, enhancing accuracy in giant resonance predictions.

Findings

Diagonal approximation affects giant quadrupole resonance strength distribution.

Including interactions between doorway states improves agreement with experimental data.

The model's results depend on the choice of Skyrme parametrization.

Abstract

A self-consistent particle-vibration coupling (PVC) model without diagonal approximation is presented. The diagonal approximation, that neglects completely the interaction between the doorway states, has been removed by taking into account the interaction between the two particle-holes inside the doorway states. As applications, isoscalar giant monopole, dipole, and quadrupole resonances in 16O are investigated based on the use of Skyrme functionals. The diagonal approximation is found to clearly impact the strength distribution of the giant quadrupole resonance, and the description of the experimental data is improved without this approximation. The impact of the diagonal approximation is analyzed in detail, especially its effect on the eigenenergies and the induced coupling between neutron and proton particle-hole configurations. The latter is a direct and physically sound effect of the improvement on our formalism. The importance of using self-consistently the full effective interaction in the PVC vertex, and the effect of its renormalization via the subtraction method, are also discussed. For completeness, we also analyze the dependence of our results on the Skyrme parametrization.