Microscopic investigations of γ-vibrational bands in neutron-deficient Kr isotopes by the triaxial projected shell model

A systematic study of yrast-, [Formula: see text]- and excited [Formula: see text]-band or [SV-bands] in [Formula: see text]Kr isotopes is performed by using the triaxial projected shell model (TPSM) approach. The TPSM approach is validated by comparing its results with available experimental data, showing satisfactory agreement. This work is carried out to study various nuclear properties, structure of yrast and [Formula: see text]-bands, signature splitting of the [Formula: see text]-vibrational bands and [Formula: see text] transition rates. For [Formula: see text]Kr isotopes, the staggering phase between even and odd spin members of the [Formula: see text]-band shows a dynamic triaxiality pattern, which is the ideal fingerprint of [Formula: see text]-softness in deformed nuclei. However, [Formula: see text]Kr exhibited a static triaxiality pattern, suggesting [Formula: see text]-rigid deformation in the collective model picture. The inclusion of quasiparticle (qp) excitations in the configuration mixing framework reversed the staggering phase from odd-I-down to even-I-down for all nuclei, except the aforementioned [Formula: see text]Kr. Further, a shape invariant analysis was performed using the TPSM calculated E2 transitions and Kumar–Cline sum rules. The analysis revealed that, after configuration mixing of qp states, the nuclear shape transforms from [Formula: see text]-rigid to [Formula: see text]-soft for all the studied krypton isotopes except [Formula: see text]Kr.