Towards NNLO accuracy in the QCD sum rule for the kaon distribution amplitude

Abstract

We calculate the O(αs) and O(αs2) gluon radiative corrections to the QCD sum rule for the first Gegenbauer moment a1K of the kaon light-cone distribution amplitude. The NNLO accuracy is achieved for the perturbative term and quark-condensate contributions to the sum rule. A complete factorization is implemented, removing logarithms of s-quark mass from the coefficients in the operator-product expansion. The sum rule with radiative corrections yields a1K(1GeV)=0.10±0.04.