Quasi-Spin Formalism and Matrix Elements in the Shell Model

Abstract

The quasi-spin formalism is used to derive useful reduction formulae for the shell model matrix elements for two-body scalar interactions between states having the same seniority quantum number. Several convenient reduction formulae are also derived in mixed configurations for both degenerate and non-degenerate cases. The seniority violating component in the Wigner interaction is estimated and its range dependence is investigated.