  In relativistic heavy ion collisions, the cross section of heavy hadron
production via the combination of a heavy quark with a light one from the
quark-gluon matter can be factorized. It is the convolution of twist-4
combination matrix elements, the parameters corresponding to the parton
distributions of the quark-gluon matter, as well as the hard partonic cross
section of heavy quark production calculable in PQCD. These parton
distributions and combination matrix elements are functions of a scaling
variable which is the momentum fraction of the heavy quark w.r.t. the heavy
hadron. In the same factorization framework, the combination matrix elements
appear in other `simpler' processes and can be extracted. Taking them as
inputs, comparing with data from RHIC and (future) LHC, we can get the parton
distributions of the quark-gluon matter just as the similar way we get those of
nucleon, pion, or photon, etc..

High Energy Physics - Phenomenology