Finite Temperature Field Theory

This thesis discusses the construction of an effective field theory (EFT) for non-relativistic Majorana fermions, shows how to use it to calculate observables in a thermal medium, and derives the effects of these thermal particles on the CP asymmetry.

Many technological applications exploit a variety of magnetic structures, or magnetic phases, to produce and optimise solid-state functionality. However, most research advances are restricted to a reduced number of phases owing to computational and resource constraints. This thesis presents an ab-initio theory to efficiently describe complex magnetic phases and their temperature-dependent properties.