Basics of Nonequilibrium Quantum Field Theory

Course description

The course is held in the second half of the spring semester 2017. It takes place on Thursdays (April: 27; May: 4, 11, 18) from 14-16 in room B1 and on Tuesdays (April: 25; May: 2, 9, 16) from 14-16 in room 119.

There has been increased interest in the dynamics of quantum fields far away from thermal equilibrium in different fields, such as high-energy particle physics (heavy ion collisions), inflationary cosmology (preheating dynamics) or AMO physics (experiments with ultracold atoms). From a theoretical point of view, it is a particular challenge to connect the far-from-equilibrium dynamics at early times with the approach to thermal equilibrium at late times.

In this course we develop the tools that are necessary to describe the nonequilibrium dynamics of quantum fields from first principles. To this end, we will use functional integral techniques on the closed time (Schwinger-Keldysh) contour to derive exact equations for nonequilibrium correlation functions. The two-particle irreducible (2PI) effective action will serve as the starting point for approximation schemes that allow for a self-consistent numerical computation of the quantum dynamics. Using these powerful techniques, we will discuss several paradigmatic phenomena of nonequilibrium quantum field theory such as particle production or (pre)thermalization.