Open charm as a probe of preequilibrium dynamics in nuclear collisions

The preequilibrium contribution to open charm production in nuclear collisions at {}s =200 A GeV is calculated and shown to be sensitive to the early time evolution of the initial minijet gluon plasma. The role of charm as a probe of the formation zone physics and correlations between momentum and space-time coordinates is emphasized. While ideal (Bjorken) correlation between the rapidity y and space-time rapidity {η} of minijet gluons suppresses greatly the preequilibrium yield, the minimal correlation with finite geometrical spread enhances the initial fusion rate by a factor {~}2 in the moderate p_⊥{~}2--6 GeV range. That is dominated by fusion of ``semihard'' p_⊥>2 GeV minijet gluons and secondary ``soft'' p_⊥2 GeV gluons from initial and final state radiation. The ``intrinsic'' charm process is negligible in the midrapidity domain.