Gross Theory of ?-Decay and Its Application to the Fermi Matrix Element

Abstract

The gross theory of nuclear β-decay proposed by Takahashi and Yamada is reinvestigated. A revised model for treating the even-odd mass difference is set up and is applied to the calculation of the squared Fermi matrix elements. The results for the superallowed transitions agree well with those expected from the isospin formalism except for the transitions from odd-odd to even-even nuclei. The isospin-forbidden Fermi transitions are also studied. The results are consistent with the existence of the gross structure in the Fermi transitions.