The $\Delta$I = 1/2 rule in non-leptonic weak decays

The authors investigate the $\Delta$I = 1/2 rule for non- leptonic decays in unified theories of weak and electromagnetic interactions. They conclude that for the eight-quark version of the Georgi-Glashow model, they get the $\Delta$I = 1/2 rule for parity-conserving decays only in the SU(3) limit. For the Salam- Weinberg model, they find that parity-conserving non-leptonic decays arise in first order of SU(3) symmetry breaking, while the parity- violating part can arise in the SU(3) limit. The violation of the $\Delta$I = 1/2rule for parity-violating decays is of first order in SU(3) breaking, whereas it is of second order in SU(3) breaking for parity-conserving decays. (5 refs).