Interactions and Field Theories

Abstract

Quantum field theories are a theoretical framework for constructing models describing particles and their interactions. The dynamics of a system can be determined starting from the Lagrangian of an interaction through canonical equations. This chapter introduces the basic formalism, illustrates the relation between symmetries of the Lagrangian and conserved quantities, and finally describes the Lagrangian for the most relevant interactions at the particle level: the electromagnetic interaction (QED), the weak interaction, and the strong interaction.