Effects of ground-state correlations on damping of giant dipole resonaces in $LS$ closed shell nuclei

TL;DR

This paper investigates how ground-state correlations influence the damping of giant dipole resonances in closed shell nuclei, revealing the importance of unconventional two-body amplitudes in the fragmentation process.

Contribution

It introduces extended RPA approaches from time-dependent density-matrix theory that include previously neglected two-body amplitudes affecting resonance damping.

Findings

Unconventional two-body amplitudes significantly impact resonance fragmentation.

Ground-state correlations alter the damping characteristics of giant dipole resonances.

Extended RPA approaches improve understanding of nuclear resonance behavior.

Abstract

The effects of ground-state correlations on the damping of isovector giant dipole resonances in $LS$ closed shell nuclei $^{16}$O and $^{40}$Ca are studied using extended random-phase-approximation (RPA) approaches derived from the time-dependent density-matrix theory. It is pointed out that unconventional two-body amplitudes of one particle--three hole and three particle--one hole types which are neglected in most extended RPA theories play an important role in the fragmentation of isovector dipole strength.