Spectral distributions of mixed configurations of identical nucleons in the seniority scheme II. Configuration-seniority scheme

Abstract

Configuration-seniority spectral distributions as well as fixed seniority and fixed total seniority and parity distributions are studied in detail for mixed configurations of identitical nucleons. The decomposition of any (1+2) -body Hamiltonian into irreducible tensors with respect to the unitary and symplectic groups in each subshell is obtained. Group theoretical methods based on the Wigner-Eckart theorem for the higher unitary groups are used to get analytical expressions for the partial widths of configuration-seniority distributions. During this derivation, various isoscalar factors for the chain SU (2..cap omega..) is contained inSp (2..cap omega..) are determined. Numerical calculations of centroid energies, partial widths, and mixing parameters are performed in the Sn and Pb nuclei with a surface delta and a gaussian interactions. Average ordinary and total seniority breaking is studied. Total seniority space truncations in the ground state region are discussed in the Pb nuclei in connections with various approximation schemes.