DOUBLE-BETA-DECAY MATRIX-ELEMENTS

The validity of the commonly assumed closure approximation has been tested by explicit calculations of the Ov beta-beta-decay matrix elements of Ge-76--> Se-76 performed in the context of quasiparticle random-phase approximation with a realistic model space. The closure approximation seems to work well for those matrix elements not very suppressed. Our results indicate that unlike the 2v decay, the Ov beta-beta-decay matrix elements are not greatly suppressed but are comparable to those of shell model calculations. They are dominated by multipoles other than 0 + and 1 +.