Wobbling excitations in odd-A nuclei with high-j aligned particles

Using the particle-rotor model in which one high-j quasiparticle is coupled to the core of triaxial shape, wobbling excitations are studied. The family of wobbling phonon excitations can be characterized by: (a) very similar intrinsic structure while collective rotation shows the wobbling feature; (b) strong B(E2;I⃗I-1) values for Δn_w=1 transitions where n_w expresses the number of wobbling phonons. For the Fermi level lying below the high-j shell with the most favorable triaxiality γ≈+20°, the wobbling phonon excitations may be more easily identified close to the yrast line, compared with the Fermi level lying around the middle of the shell with γ≈-30°. The spectroscopic study of the yrast states for the triaxial shape with -60°<γ<0 are illustrated by taking a representative example with γ=-30°, in which a quantum number related with the special symmetry is introduced to help the physics understanding.