On the QCD 2->3 contributions to the hadroproduction of heavy quarks

The use of tree level QCD 2->3 cross sections for heavy quark production are examined in detail; they are known to give significant contributions to canti c and banti b production at hadron colliders. Results are presented for the 2->3 contributions which can be reliably calculated from QCD, namely (A) the production of three isolated high psub(T) jets, (B) heavy flavour excitation where only one of the heavy quarks has large psub(T) and, (C) collinear heavy quark pair production where the pair form a single high psub(T) jet. There are no appreciable 2->3 contributions for t-quark production. (orig.)