Second RPA and correlated realistic interactions

TL;DR

This paper uses a correlated interaction derived from Argonne V18 in second RPA calculations to improve the description of nuclear resonances, highlighting the importance of higher-order configurations and self-consistency.

Contribution

It introduces a self-consistent SRPA approach with correlated interactions for better modeling of nuclear giant resonances.

Findings

Enhanced description of isovector dipole and isoscalar quadrupole resonances.

Significant effects from coupling to higher-order configurations.

Indications of the importance of self-consistency and residual three-body effects.

Abstract

We examine the response of closed-shell nuclei using a correlated interaction, derived with the Unitary Correlation Operator Method (UCOM) from the Argonne V18 potential, in second RPA (SRPA) calculations. The same correlated two-body interaction is used to derive the Hartree-Fock ground state and the SRPA equations. Our results show that the coupling of particle-hole states to higher-order configurations produces sizable effects compared with first-order RPA. A much improved description of the isovector dipole and isoscalar quadrupole resonances is obtained, thanks in part to the more fundamental treatment of the nucleon effective mass offered by SRPA. The present work suggests the prospect of describing giant resonance properties realistically and consistently within extended RPA theories. Self-consistency issues of the present SRPA method and residual three-body effects are pointed out.