We present an introductory review of the early-time dynamics of high-energy heavy-ion collisions and the kinetics of high-temperature quantum chromodynamic matter. The equilibration mechanisms in the quark–gluon plasma uniquely reflect the nonabelian and ultrarelativistic character of the many-body system. Starting with a brief exposé of the key theoretical and experimental questions, we provide an overview of the theoretical tools employed in weak coupling studies of the early-time nonequilibrium dynamics. We highlight theoretical progress in understanding different thermalization mechanisms in weakly coupled nonabelian plasmas, and discuss their relevance in describing the approach to local thermal equilibrium during the first fm/ c of a heavy-ion collision. We also briefly discuss some important connections to the phenomenology of heavy-ion collisions.
Early-time dynamics of gluon fields in high energy nuclear collisions