Next-to-Leading QCD and Finite Lifetime Effects in e+e- => t¯tH

One important task of the International Linear Collider (ILC) will be to determinethe couplings of the Higgs boson. Since the top-quark is so heavy,the top Yukawa coupling is an especially interesting quantity. It is measuredvia top-pair associated Higgs production. Within the effective theory velocityNon-Relativistic QCD (vNRQCD) we calculated the next-to-leadinglogarithmic (NLL) QCD corrections as well as the NLL finite lifetime effects,which are relevant for the first phase of the ILC with a collision energy of500GeV. The results show a strong enhancement of the total cross sectionrelative to the naive Born computation and indicate a theoretical uncertaintyof approximately 5% for the top Yukawa coupling measurement.