- lengthened the Outline effectively into an Introduction, to better show the organization & content
- incorporated all the minor corrections
- added new subsections IC6 (cosets), IIIB6 (superparticle), XC7 (10D IIB supergravity on AdS
_{5}×S^{5}), XIA8 (AdS/CFT), XIA9 (superstring), XIB9 (vertex operators), and XIB10 (lightcone algebra) - added more detail on the spinning string (in XIA3 & XIB1-2)
- changed the definition of Dirac γ-matrices to be more conventional
- finally used a spell checker

**arXiv.org**: usual formats -- pdf, ps, tex + eps figures, etc.**archive here**: tex + eps figures + pdf figures, suitable for pdftex (or TeXShop)**pdf here**: produced by pdftex (may be slightly better than arXiv.org version)

Sorry, we aren't mailing printed copies. If you still have computer-related problems, please contact your System Manager before e-mailing me.

- It's free.
- It's fast. You can download it from arXiv.org or its mirrors, just like preprints, without a trip to the library or bookstore or waiting for an order from the publisher.
- It's electronic. You can print it, but the PDF version has many advantages, like:
- Download it at work, home, etc. (or carry it on a USB flash drive), rather than carrying a book or printing multiple copies.
- Get updates just as quickly, rather than printing yet again.
- It has the usual Web links, so you can get the referenced papers just as easily.
- It has a separate "outline" window containing a table of contents on which you can click to take the main window to that item.
- You can electronically search (do a "find" on) the text.
- Save trees (and ink).
- Theft is not a problem.
- No wear or tear.
- No paper cuts.
- It can't be eaten.

- It covers many recent topics at an introductory yet nontrivial level, such as:
- supersymmetry
- general relativity
- supergravity
- strings

- It introduces many topics not appearing in other textbooks, including:
- 1/N expansion (color ordering) in QCD, including relation to random worldsheets
- spacecone (spinor helicity), including explicit calculations of 4- and 5-point S-matrices in Yang-Mills
- many useful gauges, such as Gervais-Neveu, Nielsen-Kallosh, unitary lightcone, and even string gauges in gravity
- finite N=1 supersymmetric theories

- It is
**NOT**:- a history book.
- All the other recent, comprehensive field theory texts take the "traditional" approach of covering topics in chronological (rather than logical) order, in storybook fashion. (This is strongly reminiscent of introductory classical mechanics courses that still teach Newton's laws before energy-momentum conservation.)
- This book takes advantage of hindsight, using what we now know to be the most efficient and general approaches. (For example, these other texts still quantize QED canonically, even though they know that method is inadequate for QCD. Some even claim path integrals are less rigorous, even though constructive quantum field theory has shown the opposite to be true.)
- Whenever I have questioned anyone who prefers the traditional approach, after eliminating all the spurious clichés, it all boils down to nostalgia. (I have even heard the excuse that it is useful to learn the less useful approaches simply because they ultimately failed --- certainly an excellent reason to relegate these topics to true history courses, for those who have the time and interest.) This really means that most professors simply teach things the way they learned them, and (ironically) will not bother to learn a new way, or even to check if it has any advantages. (Unfortunately, similar remarks often apply to research.)

- a cookbook. Some books race to Feynman diagrams as quickly as possible, because they either consider them the only useful part of field theory, or they think such an approach is an introductory one. One consequence is that the Higgs effect must take a back seat, and thus weak interactions are underemphasized or explained more phenomenologically.
- a concept book. All the recent texts that use a modern approach, although giving the appearance of being comprehensive except for conciseness, are curiously deficient in explicit S-matrix calculations, especially for QCD. This book both includes modern concepts and calculates with them, since the dualistic approach of concept book plus calculation book has always proved deficient for lack of two good books that work well together.
- a survey. With few exceptions, theories are described in this book at a level that allows explicit calculations.
- an art book. It covers topics that have proven useful, not those that have appealed to certain tastes.

- a history book.

- It's too broad.
- It's really big. You might never finish it. You will be exposed to too many interesting topics that you know you'll never learn.
- It's not about just LHC physics. If you read this book you'll actually learn quantum field theory, which is about more than just 1 lab.
- It takes too much time to get to Feynman diagrams. That means you might have to read the chapters out of order (as suggested in the Preface), which is too much trouble.
- It has string theory in the last couple chapters. Why would you want to learn anything that might also be applicable to string theory, & suffer guilt by association?

- It's too narrow.
- You can actually read it without reading another QFT book 1st. So if you already read another book 1st, you might have to unlearn stuff you thought you actually understood, but is really just baggage. In fact, if you learn canonical quantization of QFT you'll already have to unlearn that to understand Yang-Mills in any textbook, so better to not get as far as the Standard Model, or to read a book on just QED.
- There is too much math. Multiplying 2×2 matrices & doing Gaussian integrals, & having to look @ lots of indices. Why can't everything be explained with just words?
- There are too many words. Why can't there be more calculations? There are explicit calculations of only 4-gluon & 5-gluon amplitudes, why not 6 & 7?

- It isn't available printed on dead trees.
- How valuable can it be if I don't have to break my back lugging it around?
- Printed books are more sensually appealing: I love the way paper looks. I love the sound the pages make when I turn them. I love the feel of paper. I love the smell of paper. I love the taste of paper.

- It's too different & unconventional.
- Science is decided by tradition: It doesn't use the same explanations all the other textbooks use.
- Science is decided by authority: All the leaders in the field (or so I'm told) use other books, so they must be the best.
- Science is decided by democratic majority: Nobody else uses it to teach a course, therefore something must be wrong with it.
- Science is decided by capitalism: It's free. You get what you pay for.

- You won't get it. It might confuse you. That means you might have to think about new things. That can be hard. Maybe something awful will happen if you try it.

- information on my course based on this book:
**PHY 610-611** **overview of the course**- parts of the book used to teach my section of the string course:
**PHY 622-623**(which varies from year to year) -
**APS News article** - an interesting article on
**open source books**