Triaxiality-induced monopole-quadrupole-hexadecupole coupling in the isoscalar giant resonances of 86Ge

The isoscalar giant resonances for 86Ge are studied by the quasiparticle finite amplitude method based on the covariant density functional theory. In addition to the well-known monopole-quadrupole coupling that splits the isoscalar giant monopole resonance in axially deformed nuclei, a monopole-quadrupole-hexadecupole coupling is identified in the neutron-rich triaxially deformed nucleus Ge-86, leading to the emergence of a distinct resonance peak at the low energy side of the isoscalar monopole strength function. The transition density of the triaxiality-induced resonance peak shows a strong interplay among monopole, quadrupole, and hexadecupole vibrations. The resonance peak responds to monopole, quadrupole, and hexadecupole perturbations simultaneously, which could be regarded as a fingerprint of the triaxiality in Ge-86.

Automated summary

The study on the isoscalar giant resonances in 86Ge reveals the presence of distinct resonance peaks and density changes in axially deformed and triaxially deformed nuclei, indicating an interplay among monopole, quadrupole, and hexadecupole vibrations.