Doublet bands observed in $^{124,126,130,132}$Cs isotopes are studied using the recently developed multi-quasiparticle microscopic triaxial projected shell model (TPSM) approach. It is shown that TPSM results for energies and transition probabilities
are in good agreement with known energies and the recently measured extensive data on transition probabilities for the bands in $^{126}$Cs. In particular, it is demonstrated that characteristics transition probabilities expected for the doublet bands to originate from the chiral symmetry breaking are well reproduced in the present work. The calculated energies for $^{124,130,132}$Cs are also shown to be in reasonable agreement with the available experimental data. Furthermore, a complete set of the calculated transition probabilities is provided for the doublet bands in $^{124,130,132}$Cs isotopes.
Evidence of strong coupling of quasiparticle excitations with gamma-vibration is shown to occur in transitional nuclei. High-spin band structures in [166,168,170,172]Er are studied by employing the recently developed multi-quasiparticle triaxial proj
ected shell model approach. It is demonstrated that a low-lying K=3 band observed in these nuclei, the nature of which has remained unresolved, originates from the angular-momentum projection of triaxially deformed two-quasiparticle (qp) configurations. Further, it is predicted that the structure of this band depends critically on the shell filling: in [166]Er the lowest K=3 2-qp band is formed from proton configuration, in [168]Er the K=3 neutron and proton 2-qp bands are almost degenerate, and for [170]Er and [172]Er the neutron K=3 2-qp band becomes favored and can cross the gamma-vibrational band at high rotational frequencies. We consider that these are few examples in even-even nuclei, where the three basic modes of rotational, vibrational, and quasi-particle excitations co-exist close to the yrast line.
