Physics of heavy-quark production in quantum chromodynamics

For very heavy quark masses, QCD predicts that the inclusive hadronic pro- duction of heavy quarks is governed by quark and gluon hard scattering sub- processes. On general grounds, one expects corrections of order p/i&, where CL - 300 MeV and MQ is the heavy quark mass. At the charm mass scale, such corrections could be important, possibly accounting for the anomalies observed in the nuclear number dependence, the longitudinal momentum distributions, and beam flavor dependence of charm hadroproduction. In this paper we present a general overview of such corrections. In particular, we discuss a "coalescence" correction, which substantially alters the cross section in situations where the heavy quark is known to have low velocity relative to one or more constituents of the spectator jet. In attractive channels the result is a large enhancement. In inclusive cross sections this final state interaction effect is suppressed by only a single power of the heavy quark mass.