Electroweak corrections to the charm quark contribution to K+→π+ ν(ν)over-bar

We compute the leading-log QED, the next-to-leading-log QED-QCD, and the electroweak corrections to the charm quark contribution relevant for the rare decay K+->pi(+)nu(nu) over bar. The corresponding parameter P-c(X) is increased by up to 2% with respect to the pure QCD estimate to P-c(X)=0.372 +/- 0.015 for m(c)(m(c))=(1.286 +/- 0.013)GeV, alpha(s)(M-Z)=0.1176 +/- 0.0020, and vertical bar V-us vertical bar=0.2255. For the branching ratio we find B(K+->pi(+)nu(nu) over bar)=(8.5 +/- 0.7)x10(-11), where the quoted uncertainty is dominated by the Cabibbo-Kobayashi-Maskawa elements.