Analysis of ε'/ε in the 1/Nc expansion

In this paper it is presented a new analysis of the ratio ε'/ε which measures the direct CP violation in K →ππ decays. It is used the 1/Nc expansion within the framework of the effective chiral lagrangian for pseudoscalar mesons. The 1/Nc corrections to the hadronic matrix elements of all operators are calculated at leading order in the chiral expansion. Performing a simple scanning of the input parameters is obtained 1.5 · 10-4 ≤ ε'/ε ≤ 31.6 · 10-4. It is also investigated, in the chiral limit, the 1/Nc corrections to the operator Q6 at next-to-leading order in the chiral expansion. It is found large positive corrections which further enhance ε'/ε and can bring the standard model prediction close to the measured value for central values of the parameters. The result indicates that at the level of the 1/Nc corrections a ΔI = 1/2 enhancement is operative for Q6 similar to the one of Q1 and Q2 which dominate the CP conserving amplitude