Bottom-up thermalization in heavy ion collisions

Abstract

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 ${\alpha }^{2/5}{Q}_s$.

Comments: 11 pages; acknowledgement added; section IIIB slightly extended, version accepted for publication in Phys. Lett. B