Quasiparticle random phase approximation with inclusion of the Pauli exclusion principle - art. no. 044319

Limitations of the quasiparticle random phase approximation (QRPA) are stud ied within an exactly solvable model, with a two body interaction of Fermi type. A special attention is paid to the violation of the Pauli exclusion p rinciple (PEP) in solving the QRPA equation. A comparison of the exact solu tion, obtained by the diagonalization of a schematic nuclear Hamiltonian an d those obtained within the standard QRPA, the renormalized QRPA, the QRPA with pertubative treatment of the PEP, and the QRPA with exact consideratio n of the PEP, is presented. The agreement quality is judged in terms of the quasiparticle number operator matrix elements in the ground state and in t he first excited states, of the beta transition amplitudes, of the Ikeda su m rule, and of the nuclear matrix element for the double beta decay. We hav e found that by restoring the PEP, the QRPA solutions are considerably stab ilized and a better agreement with the exact solution is obtained.