Long-Distance Effect on CP Violation in K0-$\bar{K}^{0}$ Mixing

Abstract

Estimations are made on the long-distance effect on CP violation parameter ε in K0-K0 mixing. This effect has often been neglected because the likely dominant ππ intermediate state contribution has been thought to vanish. Here we point out a flaw in the previous arguments, and show that ππ intermediate contribution does not vanish in the actual calculation made with chiral Lagrangian method. However, the absolute magnitudes of the contributions are all found to be small, so the long-distance effect is still negligible in the estimation of ε.