Triaxiality induced monopole-quadrupole-hexadecupole coupling in the isoscalar giant resonances for $^{86}\textrm{Ge}$

TL;DR

This study reveals a novel monopole-quadrupole-hexadecupole coupling in the isoscalar giant resonances of triaxially deformed $^{86}$Ge, identified through advanced theoretical methods, indicating a new signature of nuclear triaxiality.

Contribution

The paper introduces the first identification of monopole-quadrupole-hexadecupole coupling in a triaxial nucleus using covariant density functional theory and quasiparticle finite amplitude method.

Findings

Discovery of a low-energy resonance peak due to triaxiality-induced coupling.

Strong interplay among monopole, quadrupole, and hexadecupole vibrations.

Resonance responses serve as a fingerprint of nuclear triaxiality.

Abstract

The isoscalar giant resonances for $^{86}\textrm{Ge}$ 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 triaxially deformed nucleus $^{86}\textrm{Ge}$, 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 responses to monopole, quadrupole, and hexadecupole perturbations simultaneously, which could be regarded as a fingerprint of the triaxiality in $^{86}\textrm{Ge}$.