Chirality in odd-odd triaxial nuclei

This presentation reports on recent investigations of chirality in nuclear rotation which is a novel collective feature predicted for odd-odd nuclei from angular momentum coupling considerations. New side-band partners of the yrast bands built on the πh_11/2νh_11/2 configuration were identified in several odd-odd nuclei in the A ∼ 130 region. A similar side-band partner of the yrast band built on the π(g_9/2)^-1νh_11/2 configuration was observed in ¹¹⁸I. These doublet bands, which were shown to have the same configuration, have been addressed by the microscopic 3-D Tilted Axis Cranking (TAC), and, as presented here, by a phenomenological core-proton-neutron coupling model. For triaxial nuclear shapes, both models predict left- and right-handed chiral systems built out of the three angular momenta provided by the valence proton, valence neutron, and the core rotation, which lead to spontaneous chiral symmetry breaking and the doublet bands. Small energy differences between the doublet bands suggest collective chiral vibrations.