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 $Q_s$ 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 $\alpha^{2/5}Q_s$. 
R.Baier (Bielefeld), A.H.Mueller (Columbia), D.Schiff (Orsay), and   D.T.Son (Columbia & RBRC)