  It is generally assumed that deviations from flavor SU(3) symmetry arise
entirely from quark mass-differences, reflected in the mass splittings between
strange and nonstrange members of the same SU(3) multiplet. Under this
assumption, a parametrization is proposed which expresses the ratios of
Gamow-Teller to Fermi matrix elements for nucleon and hyperon beta decays
entirely in terms of two SU(3)-invariant coupling constants $F$ and $D$ and two
parameters $\gamma$ and $\delta$ representing SU(3) breaking effects.
Therefore, in principle, measurement of this ratio for any four
beta-transitions should yield all four parameters. Available data do not show
any evidence for SU(3) breaking. Improved measurements, also for transitions
not previously measured, would provide more stringent tests.
