Physics of 'the first three fermis' in high energy heavy ion collisions

Using the (lowest-order) perturbative QCD, we argue that high energy heavy ion collisions proceed as follows: (i) 0<τ<0.3 fm/c entropy production, momenta equilibration due to gg→gg, qg→qg; (ii) 0.3<τ<2. fm/c: Gluon chemical equilibration due to gg→ng; (ii) 3<τ<τc=5-7 fm/c: Expansion of gluonic plasma till formation of the 'mixed phase', or hadronization. Much higher initial temperatures are suggested, namely Ti=400-500 MeV at RHIC and Ti=600-900 MeV at LHC. This leads to enhanced charm production and significant modifications of photon and dilepton production. (orig.)