Hyperon non-leptonic weak decays revisited

We first review the current algebra-PCAC approach to non-leptonic octet baryon 14 weak decay B --> B'pi amplitudes. The required four parameters are determined independently by Omega --> Xi pi, LambdaK and Xi (-) --> Sigma (-)gamma weak decays in dispersion theory tree order. We also summarize the recent chiral perturbation theory (ChPT) version of the eight independent B --> B'pi weak DeltaI = 1/2 amplitudes containing considerably more than eight low-energy weak constants at one-loop order.