The interacting boson fermion-fermion model is employed in the analysis of the positive-parity doublet bands in ${}^{134}\mathrm{Pr}$. It is shown that stable triaxial deformation gives rise to the experimentally observed crossing between the yrast and yrare bands built on the $\pi h_{11∕2}\otimes \nu h_{11∕2}$ configuration. The collective structure of the yrast band is basically built on the ground-state band of the triaxial core, whereas the collective structure of the yrare band is predominantly based on the $\gamma$ band of the core. The mixing between the two bands increases with angular momentum. A constant energy spacing between the two lowest positive-parity bands is predicted in other odd-odd $N=75$ nuclei with $\gamma$-soft potential energy surfaces.

• Received 4 July 2003

DOI:https://doi.org/10.1103/PhysRevC.69.017304