Bottom-up thermalization in heavy ion collisions

We describe how thermalization occurs in heavy ion collisions in the framework of perturbative QCD. When the saturation scale es is large compared to Lambda (QCD) thermalization takes place during a time of order alpha (-13/5)Q(s)(-1) and the maximal temperature achieved is alpha (2/5) Q(S). (C) 2001 Published by Elsevier Science B.V.