Proton-neutron self-consistent quasiparticle random phase approximation within the O(5) model - art. no. 044311

The self-consistent quasiparticle random phase approximation (SCQRPA) withi n the O(5) model in the coupled proton-neutron representation is analyzed. The exact vacuum wave function is used to compute all involved matrix eleme nts. A stability analysis of the stationary points is performed. A phase tr ansition from the uncoupled to the coupled stable proton-neutron regime bey ond the QRPA breakdown value of the particle-particle strength is evidenced . The excitation energies are close to the lowest stable exact eigenvalues given by the diagonalization procedure for all cases. The conditions for wh ich the Ikeda sum rule is fulfilled for all values of the particle-particle strength are pointed out.