This course provides an introduction to the modern concepts of quantum field theory, formulated in the canonical framework. Special attention is devoted to the explicit calculation of physical observables, like scattering cross-sections and decay widths. It is shown how such calculations can be performed within perturbation theory by employing Feynman rules.  The resulting higher-order perturbative corrections turn out to be infinite and therefore require a careful treatment. In this context it will be investigated whether the predictive power of the theory can be restored if the infinities are regularized properly.
A further aim of the course is to introduce the concept of  local gauge symmetries, which plays a crucial role in the description of the interactions between fundamental particles. As an example it is shown how the electromagnetic interactions can be described by invoking the gauge principle and how the corresponding gauge symmetry enables us to get a handle on the infinities of the perturbative corrections.

Instructional Modes

17 lectures and 11 exercise classes