Charge-exchange dipole excitations in deformed nuclei

Kenichi Yoshida
Phys. Rev. C 102, 054336 – Published 30 November 2020

Abstract

Background: The electric giant-dipole resonance (GDR) is the most established collective vibrational mode of excitation. A charge-exchange analog, however, has been poorly studied in comparison with the spin (magnetic) dipole resonance (SDR).

Purpose: I investigate the role of deformation on the charge-exchange dipole excitations and explore the generic features as an isovector mode of excitation.

Methods: The nuclear energy-density functional method is employed for calculating the response functions based on the Skyrme-Kohn-Sham-Bogoliubov method and the proton-neutron quasiparticle-random-phase approximation.

Results: The deformation splitting into K=0 and K=±1 components occurs in the charge-changing channels and is proportional to the magnitude of deformation as is well known for the GDR. For the SDR, however, a simple assertion based on geometry of a nucleus cannot be applied for explaining the vibrational frequencies of each K component. A qualitative argument on the strength distributions for each component is given based on the non-energy-weighted sum rules taking nuclear deformation into account. The concentration of the electric dipole strengths in low energy and below the giant resonance is found in neutron-rich unstable nuclei.

Conclusions: The deformation splitting occurs generically for the charge-exchange dipole excitations as in the neutral channel. The analog pygmy dipole resonance can emerge in deformed neutron-rich nuclei as well as in spherical systems.

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  • Received 10 August 2020
  • Accepted 12 November 2020

DOI:https://doi.org/10.1103/PhysRevC.102.054336

©2020 American Physical Society

Physics Subject Headings (PhySH)

Nuclear Physics

Authors & Affiliations

Kenichi Yoshida

  • Department of Physics, Kyoto University, Kyoto, 606-8502, Japan

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Vol. 102, Iss. 5 — November 2020

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