Production of a pseudo-scalar Higgs boson at hadron colliders at   next-to-next-to leading order
  The production cross section for pseudo-scalar Higgs bosons at hadron colliders is computed at next-to-next-to-leading order (NNLO) in QCD. The pseudo-scalar Higgs is assumed to couple only to top quarks. The NNLO effects are evaluated using an effective lagrangian where the top quarks are integrated out. The NNLO corrections are similar in size to those found for scalar Higgs boson production. 
Robert V. Harlander and William B. Kilgore