Physics 330 -- Quantum Field Theory

Physics 330 is the first course of a 3-quarter sequence on Quantum Field Theory, the theory that provides at the same time the relativistic generalization of quantum theory and the basic formalism for theories of elementary particles. In Fall 2025, this course is being given by Michael Peskin. The course meets TuTh 1:30-2:50pm in room 60-109, in the main quad next to Mem Church.

Physics 330 gives the introduction to quantum fields and Feynman diagrams. In the first week, we will quantize a field! My plan in this course is to cut corners so that we can move as quickly as possible to the prediction of actual physical processes involving electrons and photons. After this, I will discuss the famous infinities of quantum electrodynamics. I will explain "how to stop worrying and love" these infinite terms.

If you have any questions about this course, please email me at mpeskin"at"slac.stanford.edu. I would be happy to arrange a meeting at a time convenient for you.

There are many excellent books that introduce quantum field theory. You will find a selection of them in the recommended reading below. However, I do have a preference for one particular textbook, in which, remarkably, every topic is presented in just the way that I prefer. This is "An Introduction to Quantum Field Theory", by Peskin and Schroeder. I will follow this book quite closely in the lectures, though I will not cover every topic in sequence.

Further details on the administration of the course are given in this pdf: General Course Information for Physics 330

Here is a proposed lesson-by-lesson syllabus for Physics 330. This schedule might change during the course of the term:

Sept. 23: Quantization of the free scalar field
Sept. 25: The free scalar field in space-time
Sept. 30: The Dirac equation
Oct. 2: Quantization of the free spinor field
Oct. 7: Antiparticles; the space-time symmetries P, T, and C
Oct. 9: Interacting scalar fields -- perturbation theory
Oct. 14: Interacting scalar fields -- Wick's theorem
Oct. 16: Interacting scalar fields -- Feynman diagrams
Oct. 21: The S-matrix and the cross section
Oct. 23: Computation of scattering amplitudes
Oct. 28: First QED process: e+e- -> mu+mu-
Oct. 30: Compton scattering
Nov. 4: [no class: Democracy Day]
Nov. 6 Loop diagrams in QED - the electron vertex function
Nov. 11: More about the vertex function: g-2, infrared infinities
Nov. 13: The electron self-energy
Nov. 18: The S-matrix from Feynman diagrams
Nov. 20: The Ward Identity
Nov. 25, 27: [no class; Thanksgiving recess]
Dec. 2: The Photon self-energy
Dec. 4: The coupling constant alpha is not a constant

There will be a problem set every week. Problem sets and solutions will appear here:

Problem Set 1, available Sept. 25; due Oct. 2 (solutions).
Problem Set 2, available Oct. 2; due Oct. 9 (solutions).
Problem Set 3, available Oct. 9; due Oct. 16 (solutions).
Problem Set 4, available Oct. 16; due Oct. 23 (solutions).
Problem Set 5, available Oct. 23; due Oct. 30 (solutions).
Oct. 30: no problem set, but, there will be a Quiz (see below).
Problem Set 6, available Nov. 6; due Nov. 13 (solutions).
Problem Set 7, available Nov. 13; due Nov. 20 (solutions).
Problem Set 8, available Nov. 20; due Dec. 4 (solutions).

During the course of the term, there will be a Quiz and a Final Exam. Both will be take-home, but you are on your honor to solve these without collaboration. These will appear here:

Quiz -- available Friday, October 31; return by end of day Wednesday, Nov. 5. solution.
Final Exam -- available Friday, December 5; return by end of day Thursday, December 11. solution.

Here are the Quiz and Final from 2024:

Quiz ; solution.
Final Exam; solution.