A comparison of methods for determining nuclear matrix elements in first-forbidden β-decay

Abstract

In a number of recent papers we have observed that the results of matrix element extraction made by different groups are inconsistent. Since there seemed to be a correlation between the formulation used and the results obtained, the two basic treatments of the theory are compared. The comparison shows that the two methods should give very similar results unless higher-order matrix elements are unusually important. The inconsistent results appear to be caused by the way in which the matrix element extractions are performed rather than by a basic difference in the formulas. The matrix elements for the 2 − (0.959 MeV)2 + β-transition in 198Au are reviewed to illustrate how differences in technique can affect the results.