Quantum field theory is the theory of many-particle quantum systems. Just as quantum mechanics describes a single particle as both a particle and a wave, quantum field theory describes many-particle systems in terms of both particles and fields. Traditionally, quantum field theory was used in particle physics and other areas of physics to calculate properties of particles, however the study of phase transitions using field theory has become a unifying theme across most areas of physics.

This is the second of a two-volume set, based on courses taught by the author for many years at Washington University, St. Louis. The books cover quantum field theory at an introductory level appropriate for graduate students in physics, taking them in two semesters to the point where they can begin research in fields using quantum field theory, such as particle physics, nuclear physics, cosmology and astrophysics and condensed matter physics.

The topics covered in the second volume include advanced material, such as phase transitions, the renormalization group, fermions, gauge theories, the 1/N expansion, anomalies, solitons and instantons, and field theory at nonzero temperature and density.