Thermal charm production by massive gluons and quarks

We investigate charm production in an equilibrated quark-gluon plasma produced in heavy-ion collisions at RHIC and LHC. Effective quark and gluon masses are introduced from thermal QCD calculations. Assuming a Bjorken-type longitudinal expansion and including the influence of temperature dependent masses on the expansion, we determine the total number of cc pairs produced in the quarkgluon plasma phase. We calculate the charm production rate at leading order with massive gluons and quarks and compare our result to charm production by massless partons. We consider two different scenarios for the initial conditions, a parton gas with a rather long kinetic equilibration time and a minijet gas with a short equilibration time. In a parton gas, assuming mc = 1.2 GeV, we obtain a substantial enhancement over the thermal charm rate from massless quarks and gluons, up to 4.9 secondary charm quark pairs in Au+Au collisions at RHIC and 245 charm pairs in Pb+Pb collisions at the LHC. LBNL-39984 Submitted to Phys. Rev. C. 0? This work was supported in part by the Director, Office of Energy Research, Division of Nuclear Physics of the Office of High Energy and Nuclear Physics of the U. S. Department of Energy under Contract Number DE-AC03-76SF0098.