Long-Distance Effect on CP Violation in K0-K0 Mixing

Abstract

Estimations are made on the long-distance effect on CP violation parameter. E in KO-Ko mixing. This effect has often been neglected because the likely dominant 71:71: intermediate state contribution has been thought to vanish. Here we point out a flaw in the previous arguments, and show that 71:71: 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 E.