Giant Resonances based on Unitarily Transformed Two-Nucleon plus Phenomenological Three-Nucleon Interactions

TL;DR

This paper studies giant resonances in spherical nuclei using transformed two-nucleon interactions combined with a phenomenological three-nucleon force, achieving good agreement with experimental data through RPA calculations.

Contribution

It introduces a method combining unitarily transformed two-nucleon interactions with a phenomenological three-nucleon force for giant resonance calculations.

Findings

Reasonable agreement with experimental centroid energies

Effective description of ground-state energies and radii

Analysis of the Hartree-Fock reference state's role in RPA

Abstract

We investigate giant resonances of spherical nuclei on the basis of the Argonne V18 potential after unitary transformation within the Similarity Renormalization Group or the Unitary Correlation Operator Method supplemented by a phenomenological three-body contact interaction. Such Hamiltonians can provide a good description of ground-state energies and radii within Hartree-Fock plus low-order many-body perturbation theory. The standard Random Phase Approximation is applied here to calculate the isoscalar monopole, isovector dipole, and isoscalar quadrupole excitation modes of the 40Ca, 90Zr, and 208Pb nuclei. Thanks to the inclusion of the three-nucleon interaction and despite the minimal optimization effort, a reasonable agreement with experimental centroid energies of all three modes has been achieved. The role and scope of the Hartree-Fock reference state in RPA methods are discussed.