# Self-taught Quantum Field Theory

by Jon2005
Tags: field, quantum, selftaught, theory
 P: 15 I'm taking up QFT also. Here's my 2 cents: I find the following books to be useful at my level (introductory) (1) Greiner, Field Quantization: shows you in vivid, explicit detail the requisite calculations. I try to do them first on my own, of course (2) Ryder, Quantum Field Theory: it's a nice "second" book. Insightful. The chapter on canonical quantization is a must read. Also, in my case, I found it useful to do a bit of relativistic QM as preparation for QFT. Someone suggested Sakuarai's "Advanced QM". The chapter on the Dirac equation is excellent (never mind the ict).
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P: 1,204
 Quote by argonurbawono hi. i am also learning path integral and introduction to field theory, but somehow i don't like the lectures. i don't read books but only lecture notes.
There are two problems in learning QFT. The first is understanding the mathematics. If this is the problem, then you need to get as many books as possible. One of them will explain it in a way that you appreciate. In general, there are two difficulties, the Fourier transforms and conversion, and the group theory.

The second problem is understanding the physics. I think that this is best understood without the confusion created by the mathematics. If this is the problem, then you will know because you will have trouble explaining what the path integrals represent. Try this book by Feynman which is an introduction to QED for the general public:

http://www.amazon.com/exec/obidos/tg...24170?v=glance

Carl
 P: 893 I have the 1st edition of Ryder. Is it worthwhile upgrading to the 2nd edition?
 Emeritus PF Gold P: 8,147 One of the things that bugged me about Ryder (I've had it and used it for years) was no excercises. Filling in "easy to sees" is not the same. I see that Ramond (which I only got in the past year, because of recommendation here) has problem sets and at they are specifically stated to be in order of increasing difficulty. for example here is the first and last problem of the first set (covering elementary consideration of action functionals, which Ramond abbreviates AF). He directs: "...use the Action Functional as the main tool, although you may be familiar with more elementary methods of solution." A. i) Prove that the linear momentum is conserved during the motion described by $$S = \int dt \frac{1}{2} m\dot{x}^2, \dot{x} = \frac{dx}{dt}$$ ii) If $$V(x_i) = v(1-cos \frac{r}{a})$$. find the rate of change of the linear momentum. ... D.Given an AF invariant under uniform time translations, derive the expression for the associated conserved quantity. Use as an example a point particle moving in a time-independent potential. What happens if the potential is time-dependent?
 P: 46 Hey, glad to see other people regard QFT as worth learning in their spare time. You've got a fair start on me though as i'm trying to learn the math as I go. PDF Ebooks are great but you might be like me and enjoy reading away from your PC. If so I can recomend the following. The quantum theory of fields- By Steven Weinberg (ISBN 0521550017) Get volume one as it is more relevent to the theory instead of the practical applications in volume two. It's publisher is Cambridge University Press. If you realy don't mind a purely math based interpretation try 'Quantum field theory of point particals and strings' by Brian Hatfield, Addison Wesley publishers. ISBN 020111982X (I couldn't get through this due to my math being poor but it has only a small amount of string theory towards the end.The book starts at first and second quantisation). For an overview of the theory I'd suggest 'The undivided universe' by D Bohm and BJ Hiley, ISBN 0415065887. Publishers Routledge. For a truely philosophical blah session try 'An interpretive introduction to quantum field theory' by Paul Teller. ISBN 069101627. This forum is a great idea. I live in Australia and find it realy difficult to speak to anyone outside University that enjoys physics or hard science. What i'd give to visit America or Europe.
 Emeritus PF Gold P: 8,147 Patrick, I have to disagree about Peskin and Schroeder; I believe it is unsatisfactor at the start ("trust me" over and over again, which promise is not really fulfilled, and really lame motivations of things), and gets a little better later. Of course it does get you up to speed on Feynman diagrams and two-point functions real fast, and that's what a lot of students want.
Emeritus
PF Gold
P: 6,236
 Quote by selfAdjoint Patrick, I have to disagree about Peskin and Schroeder; I believe it is unsatisfactor at the start ("trust me" over and over again, which promise is not really fulfilled, and really lame motivations of things), and gets a little better later. Of course it does get you up to speed on Feynman diagrams and two-point functions real fast, and that's what a lot of students want.
That's what I tried to say, too. Don't read Peskin for any deep conceptual understanding, but it *is* rather good at getting you up and running at doing actual calculations with all the tricks. I don't know of any other book which teaches you so easily to actually *calculate* things. It's a kind of a Schaum's Series "how do I calculate feynman diagrams" (I exaggerate a bit here...)
 P: 1 Hi, this is my first post in this forum, glad to see there are people close to my current situation, I've been trying to self teach me QFT for some time and I always found that the concepts introduced by the books where disconnected with my previous knowledge on QM. (I suppose this can be a signal of poor understanding of QM on my part.) Anyway, there is a review in Amazon on the book by Mandl Quantum Field Theory, http://www.amazon.com/gp/product/cus...ustomerReviews that makes a strong point that precisely that book should be the only first book to be taken by a beginner. Despite its age, the review goes, this book takes your hand and shows you the basic stuff step by step. I don't know what your feelings regarding Mandl are, I have looked slightly at it and it seems to start low enough to catch with an ordinary knowledge of QM. There is also the book by Lahiri&Pal, http://www.amazon.com/First-Book-Qua...841429-8899045 that some people say is better than Mandl. Reading the TOC, they both look like similar "level-zero" introductions to QFT, but if someone has gone through them, perhaps he could give a more informed opinion. One drawback of those two books is that they don't even touch path integrals, so after them one should continue with more advanced/modern texts, perhaps Brown, Zee or Srednicki. Any ideas/suggestions? Thank you
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P: 1,204
 Quote by antoniobernal I've been trying to self teach me QFT for some time and I always found that the concepts introduced by the books where disconnected with my previous knowledge on QM. (I suppose this can be a signal of poor understanding of QM on my part.)
Before you suffer through learning QFT the way all the rest of us did, you might try taking a quick look at the excellent arXiv article that just recently came out:

Quantum Electrodynamics of qubits
Iwo Bialynicki-Birula, Tomasz Sowinski, May 15, 2007
Systematic description of a spin 1/2 system endowed with magnetic moment or any other two-level system (qubit) interacting with the quantized electromagnetic field is developed. This description exploits a close analogy between a two-level system and the Dirac electron that comes to light when the two-level system is described within the formalism of second quantization in terms of fermionic creation and annihilation operators. The analogy enables one to introduce all the powerful tools of relativistic QED (albeit in a greatly simplified form). The Feynman diagrams and the propagators turn out to be very useful. In particular, the QED concept of the vacuum polarization finds its close counterpart in the photon scattering off a two level-system leading via the linear response theory to the general formulas for the atomic polarizability and the dynamic single spin susceptibility. To illustrate the usefulness of these methods, we calculate the polarizability and susceptibility up to the fourth order of perturbation theory. These {\em ab initio} calculations resolve some ambiguities concerning the sign prescription and the optical damping that arise in the phenomenological treatment. We also show that the methods used to study two-level systems (qubits) can be extended to many-level systems (qudits). As an example, we describe the interaction with the quantized electromagnetic field of an atom with four relevant states: one S state and three degenerate P states.
http://www.arxiv.org/abs/0705.2121

Basically, the idea above is to strip QFT down to its essentials. Eliminate all position dependence (which creates all those nasty integrals and is responsible for all that nasty Poincare symmetry), and look at the use of QFT on the qubit system, that is, on the simplest possible quantum states.

I am writing up a post on the subject on my blog and will put it up here probably within 24 hours:
http://carlbrannen.wordpress.com/

My post will be even simpler than the above article.
 Sci Advisor P: 1,677 People have already spelled out the good QFT recommendations. But its hard to just jump into the subject without a second advanced QM course, which people don't always have as an undergrad. I recommend students in general to start with a good intro primer on particle physics before jumping into the full fledged theory perse. First get a handle on the lingo, some of the particle zoo phenomenology and to get some intuition about group theory and a cursory review of the Dirac/KG equation, scattering theory and then eventually calculating Feynman diagrams. The perfect text for an undergraduate then is Griffiths, Introduction to Elementary particles. The theory books then that follow (eg Zee, P&S, etc etc) basically derive and justify the methodology thats used. I know many experamentalists who basically have forgotten most of the nitty gritty details of the full theory perse, and instead work with the sort of level of rigor that Griffiths uses.
P: 163
 Quote by ZapperZ As everyone here has mentioned, if you do not have any knowledge of advanced QM, no amount of mathematics can help you. This is especially true if you haven't mastered Second Quantization, because that technique (and its notation) will be prevalent all over QFT. Zz.
what is "Second Quantization"?
 P: 163 I was also wondering if "Quantum Theory" by David Bohm is a good book advanced quantum mechanics?
 P: 1 Sakurai's Modern QM has a chapter on Path Integrals, which shouls make a good jumping-off point. I am looking for any one who has successfully completed the "excercises" in Ramond. Some of them seem very difficult. So much so that I can't always relate them to the material covered in the chapter!
 P: 287 One of the best books of QFT is written by Eugene Stefanovich. Its book is on arxiv. But how I wish to understand QFT: "imagination of all formulae. All formulae write differently, so that we can see their aspects. All mathematics is imaginable. Example is Brukner's thesis. It can also be found on internet." OK, Nikolic in its Myths... also wrote similar analysis of spin matrices as Brukner. One of the largest reserve for the theory of everything is to write clear theory of QFT. After this you will find many peoples, which will find TOE. Not "milion" of researchers in strings but "milion" of writers of clear QFT. We live in computer age, where only lack of imagination is obstacle to clearer QFT. Here it is a lot of experts of QFT. If every one analyses only one formula of QFT as Brukner did for QM, the new book will be here.
P: 30
For those who enjoy a 'classroom' setting, here are
Sidney Coleman's Lecture Notes on RQM and QFT:

Notes:

http://www.damtp.cam.ac.uk/user/dt281/qft/col1.pdf

http://www.damtp.cam.ac.uk/user/dt281/qft/col2.pdf

Lectures:

 Quote by CarlB Try this book by Feynman which is an introduction to QED for the general public: http://www.amazon.com/exec/obidos/tg...24170?v=glance Carl
I really love that book, it makes clear what the challenges of QFT are for the
general public and even shows the frontiers of the field as seen by Feynman.