0νββ nuclear matrix elements and the occupancy of individual orbits

The measured occupancies of valence orbits in 76Ge and 76Se are used as a guideline for modification of the effective mean field energies that results in better description of these quantities. With them, in combination with the self-consistent renormalized quasiparticle random phase approximation (SRQRPA) method that ensures conservation of the mean particle number in the correlated ground state, we show that the resulting 0νββ nuclear matrix element for the 76Ge → 76Se transition is reduced by ∼25% compared to the previous QRPA value, and therefore the difference between the present approach and the interacting shell model predictions becomes correspondingly smaller. Analogous modification of the mean field energies for the A = 82 system also results in a reduction of 0νββ matrix element for the 82Se → 82Kr transition, making it also closer to the shell model prediction.