For particle physics students concurrent enrollment in CAS PY 551 or GRS PY 751 is strongly recommended. Provides an introduction to the techniques of quantum field theory with applications to high-energy and condensed-matter physics. Topics include field equations and quantization of many-body systems; Green function and linear response theory; S-matrix and scattering theory; path integration; perturbation expansions and the Feynman rules; renormalization and effective field theories; expansion and critical exponents.