NLO QCD corrections to t anti-t H production in hadron collisions

The Higgs boson H of the Standard Model can be searched for in the channels p pbar / pp -> t tbar H + X at the Tevatron and the LHC. The cross sections for these processes and the final-state distributions of the Higgs boson and top quarks are presented at next-to-leading order QCD. To calculate these QCD corrections, a special calculational technique for pentagon diagrams has been developed and the dipole subtraction formalism has been adopted for massive particles. The impact of the corrections on the total cross sections is characterized by K factors, the ratios of the cross sections in next-to-leading order over leading order QCD. At the central scale mu_0 = (2 m_t + M_H)/2 the K factors are found to be slightly below unity for the Tevatron (K \sim 0.8) and slightly above unity for the LHC (K \sim 1.2). Including the corrections significantly stabilizes the theoretical predictions for total cross sections and for the distributions in rapidity and transverse momentum of the Higgs boson and top quarks.