A short look at ϵ′/ϵ

We analyze the theoretical implications of the new KTeV measurement of direct CP-violation in K→ππ decays. The result is found consistent with the Standard Model for low values of the strange quark mass ms. If the hadronic parameters B6(1/2) and B8(3/2) satisfy 2B6(1/2)−B8(3/2)≤2, as suggested by lattice and 1/Nc calculations, we find an upper bound of 110 MeV for ms(2 GeV). We parametrize potential new physics contributions to ϵ′/ϵ and illustrate their correlation with upper bounds on ms. Finally we discuss a non-perturbative mechanism, which is not contained in the existing calculations of B6(1/2). This mechanism enhances B6(1/2) and thereby leads to a better understanding of the ΔI=1/2 rule and the high measured value of Re (ϵ′/ϵ).