Direct CP violation in K-decay and minimal left–right symmetry scale

AbstractWe calculate the new contribution to the direct CP-violation parameter ϵ′ in K→ππ decay in the minimal left–right symmetric model with the recently-obtained right-handed quark Cabibbo–Kobayashi–Maskawa mixing. We pay particular attention to the uncertainty in the hadronic matrix element of a leading four-quark operator O−LR. We find that it can be related to the standard model electromagnetic penguin operator O8 through SU(3)L×SU(3)R chiral symmetry. Using the lattice and large Nc calculations, we obtain a robust constraint on the minimal left–right symmetric scale MWR>5 TeV from the experimental data on ϵ′