Quantum field theory: canonical and path integral approaches

This lecture, given at the 1993 School for Graduate High Energy Physicists, held in Abingdon, United Kingdom, considers economical and path integral approaches to quantum field theory. The author aims to draw together undergraduate understanding of quantum mechanics and electromagnetism to demonstrate how to quantise an arbitrary theory. A proof of Feynman rules for the perturbative evaluation of field theories, such as scalar fields, Yang-Mills and the Higgs effect, is given. The author shows that one method can assist understanding of another idea, while masking a third. Thus, Hamiltonian methods make quantum mechanics straightforward, but can hide symmetries. (UK)