Electric dipole strength and dipole polarizability in ${}^{48}$Ca within a fully self-consistent second random-phase approximation

Abstract

The second random-phase-approximation model corrected by a subtraction procedure designed to cure double counting, instabilities, and ultraviolet divergences, is employed for the first time to analyze the dipole strength and polarizability in ${}^{48}$Ca. All the terms of the residual interaction are included, leading to a fully self-consistent scheme. Results are illustrated with two Skyrme parametrizations, SGII and SLy4. Those obtained with the SGII interaction are particularly satisfactory. In this case, the low-lying strength below the neutron threshold is extremely well reproduced and the giant dipole resonance is described in a very satisfactory way especially in its spreading and fragmentation. Spreading and fragmentation are produced in a natural way within such a theoretical model by the coupling of 1 particle-1 hole and 2 particle-2 hole configurations. Owing to this feature, we may provide for the electric polarizability as a function of the excitation energy a curve with a similar slope around the centroid energy of the giant resonance compared to the corresponding experimental results. This represents a considerable improvement with respect to previous theoretical predictions obtained with the random-phase approximation or with several ab-initio models. In such cases, the spreading width of the excitation cannot be reproduced and the polarizability as a function of the excitation energy displays a stiff increase around the predicted centroid energy of the giant resonance.

References in corpus (19)

• Neutron Star Structure and the Equation of State
• Nuclear symmetry energy probed by neutron skin thickness of nuclei
• Complete electric dipole response and the neutron skin in 208Pb
• Charge, neutron, and weak size of the atomic nucleus
• The Nuclear Symmetry Energy
• The neutron skin thickness from the measured electric dipole polarizability in ${}^{68}$Ni, ${}^{120}$Sn, and ${}^{208}$Pb
• Electric dipole polarizability of ${}^{48}$Ca and implications for the neutron skin
• Neutron skin thickness in droplet model with surface width dependence: indications of softness of the nuclear symmetry energy
• Quasiparticle time blocking approximation within the framework of generalized Green function formalism
• Dipole polarizability of 120Sn and nuclear energy density functionals
• Subtraction method and stability condition in the extended RPA theories
• Giant and pigmy dipole resonances in 4He, 16,22O, and 40Ca from chiral nucleon-nucleon interactions
• Collective nuclear excitations with Skyrme-Second RPA
• Subtraction method in the second random--phase approximation: first applications with a Skyrme energy functional
• Low-lying dipole response in the stable ${}^{40,48}$Ca nuclei with the second random-phase approximation
• Electric dipole polarizability from first principles calculations
• Electric dipole response of neutron-rich Calcium isotopes in relativistic quasiparticle time blocking approximation
• Second random-phase approximation, Thouless' theorem and the stability condition reexamined and clarified
• Influence of complex configurations on properties of pygmy dipole resonance in neutron-rich Ca isotopes

Cited by in corpus (8)

• Reference Database for Photon Strength Functions
• Gamow-Teller strength in ${}^{48}$Ca and ${}^{78}$Ni with the charge-exchange subtracted second random-phase approximation
• Effective density functionals beyond mean field
• Beyond-mean-field effects on the symmetry energy and its slope from the low-lying dipole response of ${}^{68}$Ni
• A systematic study of giant quadrupole resonances with the subtracted second random--phase approximation: beyond--mean--field centroids and fragmentation
• Particle-vibration coupling for giant resonances beyond the diagonal approximation
• Soft breathing modes in neutron--rich nuclei with the subtracted second random--phase approximation
• Recent applications of the subtracted second RPA method