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epsilon'/epsilon in the 1/N_c Expansion

T. Hambye·P. H. Soldan
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Abstract

We present a new analysis of the ratio epsilon'/epsilon which measures the direct CP violation in K\toππdecays. We use the 1/N_c expansion within the framework of the effective chiral lagrangian for pseudoscalar mesons. From general counting arguments we show that the matrix element of the operator Q_6 is not protected from possible large 1/N_c corrections beyond its large-N_c or VSA value. Calculating the 1/N_c corrections, we explicitly find that they are large and positive. Our result indicates that a ΔI=1/2 enhancement is operative for Q_6 similar to the one of Q_1 and Q_2 which dominate the CP conserving amplitude. This enhances epsilon'/epsilon and can bring the standard model prediction close to the measured value for central values of the parameters.

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T. Hambye, P. H. Soldan. 1999-08-03. epsilon'/epsilon in the 1/N_c Expansion. https://arxiv.org/abs/hep-ph/9908232

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