Pairing and deformation effects in nuclear excitation spectra

2017/05/15 by A. Repko, J. Kvasil, V. O. Nesterenko +2 · 36 citations
Physics and Astronomy · #Astronomical and nuclear sciences #Atomic physics #Condensed matter physics #Dipole #Excitation #Giant resonance #Isoscalar #Isovector #Nuclear physics #Nuclear physics research studies #Nuclear reaction #Nucleon #Pairing #Physics #Quantum Chromodynamics and Particle Interactions #Quantum mechanics #Quasiparticle #Random phase approximation #Resonance (particle physics) #Superconductivity #Toroid #nucl-th

paper · pdf · doi:10.1140/epja/i2017-12406-3

published in The European Physical Journal A 53(11) (Springer Science+Business Media) · 12 pages, 12 figures

arxiv created 2017/05/15 · openalex publication_date 2017/11/01 · arxiv updated 2017/11/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06

Abstract

We investigate effects of pairing and of quadrupole deformation on two sorts of nuclear excitations,γ-vibrational K^π=2⁺ states and dipole resonances (isovector dipole, pygmy, compression, toroidal). The analysis is performed within the quasiparticle random-phase approximation (QRPA) based on the Skyrme energy functional using the Skyrme parametrization SLy6. Particular attention is paid to i) the role of the particle-particle (pp) channel in the residual interaction of QRPA, ii) comparison of volume pairing (VP) and surface pairing (SP), iii) peculiarities of deformation splitting in the various resonances. We find that the impact of the pp-channel on the considered excitations is negligible. This conclusion applies also to any other excitation except for the K^π=0⁺ states. Furthermore, the difference between VP and SP is found small (with exception of peak height in the toroidal mode). In the low-energy isovector dipole (pygmy) and isoscalar toroidal modes, the branch K^π=1^- is shown to dominate over K^π=0^- one in the range of excitation energy E < 8--10 MeV. The effect becomes impressive for the toroidal resonance whose low-energy part is concentrated in a high peak of almost pure K^π=1^- nature. This peculiarity may be used as a fingerprint of the toroidal mode in future experiments. The interplay between pygmy, toroidal and compression resonances is discussed, the interpretation of the observed isoscalar giant dipole resonance is partly revised.

Citations

• Effects of the particle-particle channel on properties of low-lying vibrational states
• Exotic modes of excitation in atomic nuclei far from stability
• Self-consistent mean-field models for nuclear structure
• Self-consistent Skyrme quasiparticle random-phase approximation for use in axially symmetric nuclei of arbitrary mass
• Microscopic linear response calculations based on the Skyrme functional plus the pairing contribution
• An HFB scheme in natural orbitals
• Toroidal resonance: Relation to pygmy mode, vortical properties, and anomalous deformation splitting