Isospin asymmetry in the continuum of the A=14 mirror nuclei

TL;DR

This study investigates isospin asymmetry in the continuum excitations of mirror nuclei $^{14}$O and $^{14}$C using HF+RPA with Skyrme interaction, revealing asymmetries near the particle threshold but not in giant resonances.

Contribution

It applies a continuum HF+RPA approach to analyze isospin asymmetry in mirror nuclei, highlighting differences in monopole and quadrupole responses near the threshold.

Findings

Asymmetry observed in IS monopole and dipole responses near threshold.

No significant asymmetry detected in giant resonance region.

Monopole transition densities exhibit halo structures near threshold.

Abstract

We study the isospin asymmetry in the isoscalar (IS) excitations in the mirror nuclei $^{14}$O and $^{14}$C by using the Hartree-Fock(HF)+random phase approximation (RPA) linear response function theory with a Skyrme interaction to take into account the continuum effect properly. The asymmetry in the IS monopole, dipole responses is pointed out in the continuum near the particle threshold with respect to the excitation energy and the sum rule strength. On the other hand, no clear sign of the asymmetry is found in the giant resonance (GR) region. In the quadrupole case, the calculated strengths of the mirror nuclei show almost the same energy dependence from the threshold to the GR region. It is found that the transition densities of the monopole response show an extended halo structure near the threshold, while those of GR region show a typical radial dependence of the compressional collective mode without any halo effect. Contrary to the transition densities of the monopole response, those of quadrupole response do not show any sign of the extended feature of wave functions neither near the threshold nor the GR energy region. Calculated strength distributions of the IS multipole states are compared with recent experimental data obtained by the multipole decomposition analysis of $\alpha $ inelastic scattering on $^{14}$O.