Exploring wobbling motion in triaxial even-even nuclei

The potential presence of wobbling motions in even-even nuclei ¹¹²Ru, ¹¹⁴Pd, ¹⁵⁰Nd, and ¹⁸⁸Os are explored by the five-dimensional collective Hamiltonian based on the relativistic density functional theory (5DCH-RDFT). The theoretical results successfully reproduce experimental energy spectra and electromagnetic transition probabilities. Analyses of the potential energy surfaces and probability density distributions in the $(\beta ,\gamma )$ deformation plane as well as the quadrupole asymmetry parameter $〈\cos 3\delta 〉$ reveal that ¹⁵⁰Nd shows near-axial symmetry in contrast to the triaxial deformation in ¹¹²Ru, ¹¹⁴Pd, and ¹⁸⁸Os. Additionally, spin coherent state (SCS) map is introduced for the first time to the 5DCH framework to visualize the geometry of angular momentum. It is revealed that the wobbling mode, characterized by oscillations of total angular momentum J about the medium axis, is present in ¹¹²Ru but absent in ¹⁵⁰Nd.