  In this talk, we present an explanation for the Delta I = 1/2 rule in
K-decays based on the premise of an infrared fixed point alpha_IR in the
running coupling alpha_s of quantum chromodynamics (QCD) for three light quarks
u,d,s. At the fixed point, the quark condensate spontaneously breaks scale and
chiral SU(3)_L x SU(3)_R symmetry. Consequently, the low-lying spectrum
contains nine Nambu-Goldstone bosons: pi,K,eta and a QCD dilaton sigma. We
identify sigma as the f_0(500) resonance and construct a chiral-scale
perturbation theory CHPT_sigma for low-energy amplitudes expanded in alpha_s
about alpha_IR. The Delta I = 1/2 rule emerges in the leading order of
CHPT_sigma through a sigma-pole term K_S --> sigma --> 2 pi, with a K_S-sigma
coupling fixed by data on 2 gamma --> 2 pi^0 and K_S --> 2 gamma. We also
determine R_IR ~ 5 for the nonperturbative Drell-Yan ratio at alpha_IR.
