A First Course in String Theory

By Barton Zwiebach
Cambridge University Press, 2004
578 pages

Back cover text

A First Course in String Theory gives a self-contained explanation of string theory at a level that is truly understandable to advanced undergraduates, beginning graduate students, and physicists in all areas of research.
Dealing with string theory in two parts, the book first covers the classical and quantum dynamics of relativistic strings and gives a brief introduction to superstrings. The second part covers D-branes, string thermodynamics, and various aspects of T-duality. It also covers possible applications: the Standard Model on D-branes, the calculation of the entropy of black holes, and the string-theory/gauge-theory correspondence.
With more than 150 problems and 100 exercises, this book is ideal for introductory courses in string theory, as well as for self-study.

Barton Zwiebach is presently Professor of Physics at the Massachusetts Institute of Technology. His graduate work in physics was done at the California Institute of Technology, obtaining his doctorate in 1983, working under the supervision of Professor Murray Gell-Mann (Nobel Prize Physics, 1969).

From the Foreword by David Gross

Zwiebach is an accomplished string theorist, who has made many important contributions to the theory, especially to the development of string field theory. In this book he presents a remarkably comprehensive description of string theory that starts at the beginning, assumes only minimal knowledge of advanced physics, and proceeds to the current frontiers of physics. Already tested in the form of a very successful undergraduate course at MIT, Zwiebach's exposition proves that string theory can be understood and appreciated by a wide audience.

From the Preface

The idea of having a serious string theory course for undergraduates was first suggested to me by a group of MIT sophomores sometime in May of 2001. ...
A First Course in String Theory should be accessible to anyone who has been exposed to special relativity, basic quantum mechanics, electromagnetism, and introductory statistical physics. Some familiarity with Lagrangian mechanics is useful but not indispensable. ...
Throughout the book the material is taught in a self-contained way, and very little must be taken on faith.

From Chapter 1

String theory is an excellent candidate for a unified theory of all forces of nature. It is also a rather impressive prototype of a complete theory of physics. In string theory all forces are truly unified in a deep and significant way. In fact, all the particles are unified. String theory is a quantum theory, and because it includes gravitation, it is a quantum theory of gravity. ...
In string theory, each particle is identified as a particular vibrational mode of an elementary microscopic string. ...
Let us begin by noting two broad subdivisions. There are open strings, and there are closed strings. ... Since open strings generally can close to form closed strings, we do not consider theories with only open strings. The second subdivision is between bosonic string theories and superstring theories. Bosonic strings live in 26 dimensions, and all of their vibrations represent bosons. Since they lack fermions, bosonic string theories are not realistic. They are, however, much simpler than the superstrings, and most of the important concepts in string theory can be explained in the context of bosonic strings. The superstrings live in ten-dimensional spacetime, and their spectrum of states includes bosons and fermions. In fact, these two sets of particles are related by supersymmetry. Supersymmetry is therefore an important ingredient in string theory. All realistic models of string theory are built from superstrings. In all string theories the graviton appears as a vibrational mode of closed strings. In string theory gravity is unavoidable. ...
All in all, we see that string theory is a truly unified and possible unique theory. ... It is almost certain that string theory will give rise to a new conception of spacetime. ... This book will explain in detail how string theory, at least in its simplest form, is nothing but the quantum mechanics of classical relativistic strings. (pp. 6-8)

From Chapter 13

We have so far studied bosonic string theories, both open and closed. ...
Realistic string theories, however, must also contain the states of fermionic particles. ... To obtain them we need superstring theories. We will not study superstrings in detail in this book. A proper explanation of the necessary background material would take too long. Here we would like to give you a general idea about superstrings. (p. 262)

From Chapter 15

Intersecting brane models are particularly attractive, but they are by no means the only avenues that have been investigated in order to construct string models of particle physics. We had a detailed look at the intersecting brane models because they are simple enough and can be understood very concretely.
In summary, while a fully realistic model of particle physics has not yet been built in string theory, consistent progress towards this goal has been made. As we have seen, there are now string models which have precisely the particle content of the Standard Model. The significance of this development will depend on the ultimate success or failure of the models and what we learn from them. The intersecting brane models cannot be said to be fully realistic because symmetry breaking remains to be worked out. ...
If symmetry breaking works out in detail in some consistent string model, we would have shown that the Standard Model in its full glory can occur as a solution of string theory. ... From a theoretical perspective, however, we would not quite be done yet. String theory is a theory of all the interactions, and it includes gravity. We need a solution of string theory where the Standard Model is embedded into a consistent cosmology. The cosmological history of the universe must also emerge correctly. Only recently have physicists begun to ponder these questions. (pp. 344-346)