Analysis of \epsilon'/\epsilon in the 1/N_c Expansion
Abstract
We present a new analysis of the ratio \epsilon'/\epsilon which measures the direct CP violation in K\to\pi\pi decays. We use the 1/N_c expansion within the framework of the effective chiral lagrangian for pseudoscalar mesons. The 1/N_c corrections to the hadronic matrix elements of all operators are calculated at leading order in the chiral expansion. Numerically, doing a simple scanning of the input parameters we find 1.5 \cdot 10^{-4}\leq \epsilon'/\epsilon \leq 31.6\cdot 10^{-4}. We also investigate, in the chiral limit, the 1/N_c corrections to the operator Q_6 at next-to-leading order in the chiral expansion. We find large positive corrections which can further enhance \epsilon'/\epsilon and bring the standard model prediction close to the measured value for central values of the parameters. Our result indicates that a \Delta I=1/2 enhancement may be operative for Q_6 similar to the one of Q_1 and Q_2 which dominate the CP conserving amplitude.
Keywords
Cite
@article{arxiv.hep-ph/9906434,
title = {Analysis of \epsilon'/\epsilon in the 1/N_c Expansion},
author = {T. Hambye and G. O. Koehler and E. A. Paschos and P. H. Soldan},
journal= {arXiv preprint arXiv:hep-ph/9906434},
year = {2014}
}
Comments
49 pages, 10 figures. Minor changes in wording, references corrected. To appear in Nuclear Physics B