Two-loop electroweak corrections to Higgs production at hadron colliders

We compute the two-loop electroweak corrections due to the top quark to the gluon fusion production cross section of an intermediate-mass Higgs boson. This result, together with the previously known contribution due to the light fermions, allows a complete determination of the two-loop electroweak corrections to this production cross section. For Higgs mass values above 120 GeV the top corrections have opposite sign of the light fermions contribution, however they are always smaller in size reaching at most 15% of the latter. The total electroweak corrections to the gluon fusion production cross section for 115 GeV < m_H < 2 m_W range from 5% to 8% of the lowest order term.