Ground state particle-particle correlations and double-beta decay

A self-consistent formalism for the double-beta decay of Fermi type is provided. The particle-particle channel of the two-body interaction is considered first in the mean field equations and then in the quasiparticle random phase approximation (QRPA). The resulting approach is called the QRPA with a self-consistent mean field (QRPASMF). The mode provided by QRPASMF does not collapse for any strength of the particle-particle interaction. The transition amplitude for double-beta decay is almost insensitive to the variation of the particle-particle interaction. Comparing it with the result of the standard pnQRPA, it is smaller by a factor of 6. The prediction for transition amplitude agrees quite well with the exact result. The present approach is the only one that produces a strong decrease of the amplitude and at the same time does not alter the stability of the ground state. (C) 2001 Elsevier Science.