Soft Dipole Resonances in ⁸He and ⁸C

¹ General Education, Faculty of Engineering, Osaka Institute of Technology, Osaka, Osaka 535-8585, Japan
² Research Center for Nuclear Physics (RCNP), Osaka University, Ibaraki 567-0047, JapanInsert
³ School of Engineering and Applied Sciences, Nuclear Research Centre, National University of Mongolia, Ulaanbaatar 210646, Mongolia
⁴ Nuclear Reaction Data Centre, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan

^* e-mail: takayuki.myo@oit.ac.jp
^** e-mail: odsuren@seas.num.edu.mn
^*** e-mail: kato@nucl.sci.hokudai.ac.jp

Published online: 28 October 2024

Abstract

Soft dipole resonances in ⁸He and ⁸C are investigated by applying the complex scaling method to the α + N + N + N + N five-body model for the isospin T = 2 system. The 1⁻ excited resonant states are calculated at (E_x, Γ) = (14.0, 21.1) MeV and (12.7, 24.0) MeV for ⁸He and ⁸C, respectively. From the analyses of the configuration mixing and the spatial properties, the soft dipole resonances of two nuclei are understood to be the vibrational states of valence nucleons and the α core. They are also seen to have a good isospin symmetry. In contrast, the ground states of two nuclei show different spatial properties indicating the symmetry breaking due to the Coulomb repulsion of valence protons in ⁸₆C₂.