Nuclear collective excitations using correlated realistic interactions: the role of explicit RPA correlations

Abstract

We examine to which extent correlated realistic nucleon-nucleon interactions, derived within the Unitary Correlation Operator Method (UCOM), can describe nuclear collective motion in the framework of first-order random-phase approximation (RPA). To this end we employ the correlated Argonne V18 interaction in calculations within the so-called "Extended" RPA (ERPA) and investigate the response of closed-shell nuclei. The ERPA is a renormalized RPA version which considers explicitly the depletion of the Fermi sea due to long-range correlations and thus allows us to examine how these affect the excitation spectra. It is found that the effect on the properties of giant resonances is rather small. Compared to the standard RPA, where excitations are built on top of the uncorrelated Hartree-Fock (HF) ground state, their centroid energies decrease by up to 1 MeV, approximately, in the isovector channel. The isoscalar response is less affected in general. Thus, the disagreement between our previous UCOM-based RPA calculations and the experimental data are to be attributed to other effects, mainly to a residual three-body force and higher-order configurations. Ground-state properties obtained within the ERPA are compared with corresponding HF and perturbation-theory results and are discussed as well. The ERPA formalism is presented in detail.

13 pages, incl. 7 figures and 1 table

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• Second random-phase approximation, Thouless' theorem and the stability condition reexamined and clarified
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• Chiral NNLO${}_{\text{sat}}$ descriptions of nuclear multipole resonances within the random phase approximation
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• Nuclear multipole responses from chiral effective field theory interaction
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• Reply to the Comment on 'Pygmy dipole response of proton-rich argon nuclei in random-phase approximation and no-core shell model'
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