The charm-quark contribution to epsilonK and Delta MK
Abstract
Neutral Kaon mixing plays an important role in the phenomenology of the standard model and its extensions because of its sensitivity to high-energy scales. In particular epsilonK, parameterising indirect CP violation in the neutral Kaon system, serves as an important constraint on models of new physics and is well suited for the indirect search for heavy new particles. In order to exploit this potential, a precise prediction of the standard-model background is crucial. I give a short summary of the standard-model prediction of epsilonK, and present our recent NNLO QCD calculation of the charm-quark contribution etacc to the |Delta S| = 2 effective Hamiltonian. We find a large 36% shift with respect to the NLO value that leads to etacc = 1.87(76), shifting the standard-model prediction to |epsilonK| = 1.81(28) x 10-3.