Effects of orbital occupancies and spin-orbit partners on neutrinoless double-beta decay rates

Abstract

Neutrinoless double beta decay of the{76}Ge, {82}Se, {128}Te, {130}Te and{136}Xe nuclei is discussed in terms of the associated nuclearmatrix element (NME). The effects of the size of the single-particlemodel space and the occupancies of individual orbits on the NME arediscussed by using the proton-neutron quasiparticle random-phaseapproximation (pnQRPA) with effective, G-matrix-derived nuclear forces.It is found that only in some cases the orbital occupancies play adecisive role for the size of the NME, whereas the inclusion of all thespin-orbit partners is essential to achieve a NME of reasonablequality. The obtained results are compared with published results ofother models.