Quantum field thermalization in expanding backgrounds

Understand

The 2PI effective action formalism for quantum fields out of equilibrium is set up in an expanding (Friedmann-Robertson-Walker) background.

• We write down and solve the evolution equations for a phi^4 model at NLO in a coupling expansion.
• We comment on issues of renormalization, lattice discretization and the range of applicability of the approach.
• A number of example calculations are presented, including thermalization and (p)reheating.