A $\beta$-Decay Matrix Element for a Deformed Core Model

The $\mathrm{ft}$ value for an allowed unfavored $\beta$ transition, calculated on a deformed core+single-particle model, is ≤3 times the single-particle value and about 4 percent of the observed value. The deformations of initial and final states were based on their quadrupole moments. The calculation indicates that for this model core orthogonality generally does not account for the difference between allowed favored and unfavored $\mathrm{ft}$ values.