B. W. Lee has shown that, in the limit $\delta =0\mathrm{}$, where $\delta =\frac{(m_{\Sigma }-m_{\Lambda })}{(m_{\Xi }-m_N)}$, a ${\lambda }_6$-type pole model for parity-conserving (p.c.) hyperon decay gives rise to an effective interaction which behaves like ${\lambda }_7$. Here we generalize this result to include a 27-plet baryon pole, and show that, under certain plausible conditions, the generalization holds to first order in $\delta$. As a result of this generalization, the p.c. decay amplitudes satisfy two sum rules which have previously been derived for parity-violating amplitudes from the $\mathrm{SU}\left(3\right)\mathrm{}$ properties of the Cabibbo currentXcurrent interaction.

• Received 21 April 1966

DOI:https://doi.org/10.1103/PhysRev.149.1200