Interacting boson model plus broken-pair description of high-spin dipole bands

The interacting boson model with broken pairs has been extended to include mixed proton-neutron configurations in the fermion model space. The extended version of the model has been used to describe high-spin bands in the transitional nucleus ${}^{136}$Nd. Model calculations reproduce ten bands of positive and negative parity states, including the two dipole high-spin structures based on the $(\pi h_{11/2}{)}^2$ $(\nu h_{11/2}{)}^2$ configuration.