What Is a Quantum Field Theory?

A revised edition of this lively introduction to QFT for readers with a background in undergraduate mathematics.

This revised edition introduces the main ideas of quantum field theory (QFT) for readers with knowledge of undergraduate mathematics but no previous background in physics. It focuses on in-depth understanding of the methods and concepts used by physicists, including renormalization, rather than experimental aspects of the theory.Quantum field theory (QFT) is one of the great achievements of physics, of profound interest to mathematicians, yet standard texts often assume a physicist's background or adopt an abstract mathematical perspective. This thoroughly updated edition bridges that gap. While maintaining a rigorous approach wherever possible, it focuses on explaining what physicists do and why, using precise mathematical language. Written for readers with a background in mathematics but no prior knowledge of physics, and largely self-contained, it presents both essential physical ideas and the necessary mathematical tools in detail. This revised edition has been improved throughout, with many clarifications to the text and the inclusion of solutions to selected exercises to enhance its use for self-study. It will appeal to mathematicians seeking an accessible path into QFT and to physics students wanting greater rigor.