Origin of I=1/2 Rule for Kaon Decays: QCD Infrared Fixed Point
Abstract
We replace ordinary chiral SU(3)L * SU(3)R perturbation theory CHPT3 by a new theory CHPTsigma based on a low-energy expansion about an infrared fixed point alphaIR for 3-flavor QCD. At alphaIR, the quark condensate <barqq>vac =\= 0 induces nine Nambu-Goldstone bosons: pi, K, eta and a 0++ QCD dilaton sigma. Physically, sigma appears as the f0(500) resonance, a pole at a complex mass with real part < mK. The I = 1/2 rule for nonleptonic K-decays is then a consequence of CHPTsigma, with a KS-sigma coupling fixed by data for KS0 --> gamma gamma and gamma gamma --> pi pi. We estimate RIR ~ 5 for the nonperturbative Drell-Yan ratio R = sigma(e+e- --> hadrons)/sigma(e+e- --> mu+mu-) at alphaIR.
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