Two-neutrino double beta decay of 76Ge within deformed QRPA Original Research Article

The effect of deformation on the two-neutrino double decay (2νββ-decay) for ground state transition View the MathML source is studied in the framework of the deformed QRPA with separable Gamow–Teller residual interaction. We found that when the parent and daughter nuclei have different deformations, the 2νββ-decay matrix element is suppressed with respect to the case of 2νββ decay between nuclei having the same deformation, in particular, spherical going to spherical. An advantage of this suppression mechanism in comparison with that associated with ground state correlations is that it allows a simultaneous description of the single β and the 2νββ-decay. By performing a detail calculation of the 2νββ-decay of 76Ge, it is found that the states of intermediate nucleus lying in the region of the Gamow–Teller resonance contribute significantly to the matrix element of this process.