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Welcome to the home page of QFT II for Fall 2019. Quantum field theory is the mathematical framework of all of particle physics and the indispensable language of a large body of statistical mechanics and of quantum many body physics. It is an incredibly rich subject that you will keep learning for the rest of your scientific life.

Learning QFT is qualitatively different from learning other advanced subjects, such as quantum mechanics and classical general relativity, which have a more established logical framework, and have been formalized even to the satisfaction of mathematicians. QFT is still an open subject, close to the conceptual frontier of theoretical physics. It is a work in progress, enriched by new viewpoints, simplified and extended in unexpected directions by each generation of theorists.

This is the second semester of a two-semester sequence. The material of QFTI (PHY610) will be assumed as prerequisite. First year graduate students who have taken QFT elsewhere may be able to take this class, depending on their level of preparation.

** Course Outline:**
We will start by reviewing and
deepening our understanding of renormalization in QFT. We will review
the renormalization of UV divergences in perturbation theory and then
introduce the Wilsonian viewpoint on QFT - notably the connection
between renormalization and critical phenomena. We will then move on to
new topics: Abelian and non-abelian gauge theories and their
path-integral quantization. One-loop calculations in quantum
electrodynamics and Yang-Mills theory. Asymptotic freedom of
non-abelian gauge theories. Anomalies. Spontaneous symmetry breaking of
global symmetries. Chiral Lagrangians (example of pion physics).
Spontaneous symmetry breaking of gauge symmetries. Phases of gauge
theories. Introduction to the Standard Model of particle physics.

I plan to mostly use parts of Srednicki, Weinberg vol II, and Peskin&Schroeder. For the the Wilsonian RG, Cardy's book is a good reference. Other material and notes will be used for special topics.

M. Srednicki, Quantum Field Theory, Cambridge University Press.

Very clear short chapters. Particularly strong on technical details and explicit calculations.

A draft of the book is available on the author's webpage.

S. Weinberg, The Quantum theory of Fields, Cambridge University Press. Three volumes.

By one of the masters of the subject. Not an easy read but definitely worth it.

Volume I provides a compelling case that the formalism of quantum field theory inevitably arises from the marriage of special relativity and quantum mechanics. Probably best to read after you have mastered the basics of QFT. Volume II has some of the best treatments of several advanced topics (unsurpassed is the treatment of symmetry breaking, for example). Ditto for Volume III (on supersymmetry). Cumbersome notation throughout -- the use of four-component spinors in volume three is infuriating.

J. Cardy, Scaling and Renormalization in Statistical Physics, Cambridge University Press.

A gem. Very physical treatment of renormalization in the context of statistical mechanics.

Other textbooks:

To get oriented in a difficult subject that will likely challenge you both conceptually and technically, I very strongly recommend reading Zee's book:

A. Zee, Quantum Field Theory in a Nutshell, Princeton University Press

Zee gets to the core ideas keeping the technicalities to a minimum and is fun to read. Perfect for bedtime reading. We won't it use it as the main textbook because we'll need to develop the calculational machinery in greater depth.

M. D. Schwartz, Quantum Field Theory and the Standard Model, Cambridge University Press.

Recent textbook, building up to a comprehensive treatment of the Standard Model.

M. Peskin and D. Schroder, An introduction to quantum field theory, Addison-Wesley.

P&S has been the standard textbook for several years, and still has a lot of useful material. Chapter 5 (scattering process in QED) and Part II (an attempt to bridge the gap between the diagrammatic and Wilsonian viewpoints on renormalization theory) are particularly recommended.

T. Banks, Modern Quantum Field Theory: A concise introduction, Cambridge University Press.

Short and insightful tour of the subject.

A classic. While somewhat dated, it contains an impressive amount of information. Still extremely useful as a reference for many details that cannot be easily found elsewhere.

F. Strocchi, An Introduction to Non-Perturbative Foundations of Quantum Field Theory, Oxford Science Publications.

More specialized and mathematical. These lecture notes give a clear introduction to various approaches to the axiomatic foundations of QFT.

ZamolodchikovQFT1Notes

RenormalizationGroupReferences

Polchinski

WilsonKogut

Lectures on EFT:

for a review of the standard hep-th approach, https://arxiv.org/abs/0802.0634

Tong briefly discusses some more modern ideas and emphasizes 't Hooft anomalies, http://www.damtp.cam.ac.uk/user/tong/gaugetheory/3anom.pdf

Homework:

HW1 (due Sept 13)

HW1solutions

HW2 (due Sept 20)

HW2solutions

HW3 (due Oct 4)

HW3solutions

HW4 (due Oct 18)

HW4solutions

HW5 (due Nov 1)

HW5solutions

HW6 (due Nov 13)

HW6solutions

HW7 (due Nov 22)

HW7solutions

HW8 (due Dec 11)

HW8solutions

**Final: December 17,
5:30pm-8pm, in the usual classroom**

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