Low-energy isovector and isoscalar dipole response in neutron-rich nuclei

Scientific paper - Original scientific paper

• Author: Dario Vretenar
• Author: Y. F. Niu
• Author: Nils Paar
• Author: Jie Meng
• Author's institution: University of Zagreb; Faculty of Science; (Department of Physics)
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract (english)

The self-consistent random-phase approximation, based on the framework of relativistic energy density functionals, is employed in the study of isovector and isoscalar dipole response in 68Ni, 132Sn, and 208Pb. The evolution of pygmy dipole states (PDSs) in the region of low excitation energies is analyzed as a function of the density dependence of the symmetry energy for a set of relativistic effective interactions. The occurrence of PDSs is predicted in the response to both the isovector and the isoscalar dipole operators, and its strength is enhanced with the increase in the symmetry energy at saturation and the slope of the symmetry energy. In both channels, the PDS exhausts a relatively small fraction of the energy-weighted sum rule but a much larger percentage of the inverse energy-weighted sum rule. For the isovector dipole operator, the reduced transition probability B(E1) of the PDSs is generally small because of pronounced cancellation of neutron and proton partial contributions. The isoscalar-reduced transition amplitude is predominantly determined by neutron particle-hole configurations, most of which add coherently, and this results in a collective response of the PDSs to the isoscalar dipole operator.

• Keywords (english): nuclear energy density functional; dipole response; quasiparticle random phase approximation
• Language: english
• Publication type: Scientific paper - Original scientific paper
• Publication status: Published
• Peer review: Peer review - international
• Publication version: Published version
• Journal title: Physical Review C - Nuclear Physics
• Numbering: vol. 85, no. 4, 044317
• p-ISSN: 0556-2813
• e-ISSN: 1089-490X
• DOI: https://doi.org/10.1103/PhysRevC.85.044317
• URN:NBN: urn:nbn:hr:217:912983
• Publication: 2012
• Project: Number: 119-1191005-1010; Title (croatian): Nuklearna struktura i nuklearna astrofizika; Leader: Dario Vretenar; Jurisdiction: Croatia; Funding stream: ZP
• Document URL: http://link.aps.org/doi/10.1103/PhysRevC.85.044317
• Type of resource: Text
• Access conditions: Open access
• Public note: Copyright (2012) by the American Physical Society. Received 24 February 2012; revised manuscript received 2 April 2012; published 17 April 2012.
• Created on: 2019-11-16 10:53:03