Extended random-phase-approximation study of fragmentation of giant quadrupole resonance in $^{16}$O

TL;DR

This paper investigates the damping and fragmentation of the giant quadrupole resonance in oxygen-16 using advanced RPA methods that incorporate ground-state correlations, revealing significant strength fragmentation even with limited configurations.

Contribution

It introduces an extended RPA approach based on time-dependent density-matrix theory to study resonance damping and fragmentation in $^{16}$O.

Findings

Ground-state correlations cause strong fragmentation of quadrupole strength.

Fragmentation occurs even with limited two particle--two hole configurations.

Extended RPA effectively captures resonance damping phenomena.

Abstract

The damping of isoscalar giant quadrupole resonance in $^{16}$O is studied using extended random-phase-approximation approaches derived from the time-dependent density-matrix theory. It is pointed out that the effects of ground-state correlations bring strong fragmentation of quadrupole strength even if the number of two particle--two hole configurations is strongly limited.