Coherent-state theory for the proton-neutron quasispin group

Abstract

An extended coherent-state theory 1, 2) is used to give a simple construction for the matrix elements of the proton-neutron sp(4) quasispin algebra. A very simple analytical expression is given for the matrix elements of the sp(4) generators valid for all cases where initial and final states are multiplicity-free with respect to the U(1) x SU(2) n, T subalgebra. In the more general case, involving multiplicity, the most natural orthonormal basis constructed by the coherent-state method leads to many-nucleon states in the seniority scheme which are approximately labelled by Tp, the isospin of the p nucleon pairs coupled to J = 0, T = 1.