Hyperon Non-leptonic Weak Decays in the Chiral Perturbation Theory I
  Hyperon non-leptonic weak decay amplitudes are studied in the chiral perturbation theory. We employ the low energy effective weak Hamiltonian which contains the perturbative QCD correction. To include the non-perturbative QCD effect, quark currents of the effective Hamiltonian are substituted with hadronic currents which are color singlet and are derived by the chiral perturbation theory. We find that the amplitudes caused by the product of hadronic currents are small. It reproduce the small amplitudes of $\Delta I=3/2$, which are derived by the strong interaction correction. 
K. Takayama and M. Oka