New type of chiral motion in even–even nuclei: the 138Nd case

Abstract

The phenomenological generalized coherent state model Hamiltonian is amended with a many body term describing a set of nucleons moving in a shell model mean-field and interacting among themselves with pairing, as well as with a particle–core interaction of spin–spin type. The model Hamiltonian is treated in a restricted space consisting of the core projected states associated to the band ground, and and two proton aligned quasiparticles coupled to the states of the collective dipole band. The chirally transformed particle–core states are also included. The Hamiltonian contains two terms which are not invariant to the chiral transformations relating the right-handed frame and the left-handed ones , , where are the angular momenta carried by fermions, proton and neutron bosons, respectively. The energies defined with the particle–core states form four bands, two of them being degenerate in the present formalism, while the other two exhibit chiral properties reflected by energies, electromagnetic properties and the energy staggering function. A numerical application for 138Nd shows a good agreement between results and the corresponding experimental data.