Interpretation of the data  Double beta decay  Matrix elements

Comparison with predictions for $\beta\beta 2\nu$ decay.

Quite firm predictions based on QRPA for $\beta\beta 2\nu$ half lives in various nuclei have been obtained by a group at Caltech. The agreement between measured and calculated half-lives in ⁷⁶Ge, ⁸²Se, ¹⁰⁰Mo, in which $\beta\beta 2\nu$ has been observed directly, is quite good, within a factor 2 or 3. The agreement is also reasonable in ¹²⁸Te and ¹³⁰Te, for which geochemical data are available. The Strasbourg-Madrid group has performed realistic shell model calculations for ⁷⁶Ge and ⁸²Se. They too are in reasonable agreement with measured values. Shell model predictions for ⁴⁸Ca, a nucleus which is particularly simple to describe, also reproduce well the measured value.