Thermalization in ultrarelativistic heavy ion collisions: Parton cascade approach

A parton cascade model is formulated for ultrarelativistic heavy ion collisions. The model is used to determine the degree of thermalization, as well as energy and baryon number densities in central collisions of heavy ions at ultrarelativistic energies. It is shown that the energy densities required for quark-gluon plasma formation can easily be reached at $\sqrt{s_{\mathrm{NN}}}$ less than 100 GeV.