Role of chirality in angular momentum coupling for [Formula Presented] odd-odd triaxial nuclei: [Formula Presented]

Nearly degenerate partner bands observed in [Formula Presented] odd-odd triaxial nuclei are interpreted as a manifestation of chirality in the intrinsic reference frame. A phenomenological approach, based on a core-particle-hole coupling model, has been developed to address the experimental observables. This laboratory-frame model, in which chiral symmetry has been restored, includes a triaxial core, a particle/hole single-particle Hamiltonian, and quadrupole-quadrupole interactions. The optimal model parameters are investigated. The results of the calculations indicate the existence of pairs of [Formula Presented] states with the same spin, parity, and similar excitation energy forming partner bands that are nearly degenerate over a range of spins. These calculated partner bands are consistent with the chiral band interpretation and are in agreement with experimental observations in this region. This model has been applied to excited states in [Formula Presented] which have been studied via the [Formula Presented] reaction using γ-ray spectroscopic techniques. In addition to the yrast [Formula Presented] band, the partner band was observed with experimental properties consistent with the same [Formula Presented] configuration. These doublet bands resemble those observed systematically for several [Formula Presented] isotones of [Formula Presented].