= Comparative half-life
{title2=$ft$}
The product of a dimensionless beta-decay statistical phase-space factor $f$ and the partial <half-life> $t$ for the transition. The tabulated $\log ft$ normally means $\log_{10}[ft/(1\,\mathrm s)]$. Factoring out this approximate <phase space> dependence allows comparisons of nuclear weak matrix elements. Strong superallowed <Fermi transitions> have small $\log ft$; <forbidden beta decays> generally have larger values, with nuclear-structure exceptions and overlaps between categories.
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