American Scientist

The Quantum Theory of Fields: Volume III. Supersymmetry. Steven Weinberg. 448 pp. Cambridge University Press, 2000. $49.95.

Supersymmetry: Unveiling the Ultimate Laws of Nature. Gordon Kane. xiii + 199 pp. Helix Books/Perseus Publishing, 2000. $26.

The Standard Model of elementary particle physics has been verified to high precision; however, there are a few conceptual difficulties that indicate that new physics is to be expected beyond. One would like to know, for example: Why are there 19 arbitrary parameters, and how can that number be reduced? What is the origin of the three fermion generations, and how can their masses be predicted? What is the solution to the gauge hierarchy problem? Why does the cosmological constant vanish? Why is our world four-dimensional, and how is gravity included at the quantum level? The framework of supersymmetry, which is the subject of these two books, has led to new approaches to answering these questions.

Nobel Laureate Steven Weinberg presents a self-contained, up-to-date and comprehensive introduction to supersymmetry in the third volume of The Quantum Theory of Fields. The book offers a well-balanced representation of the conceptual framework and phenomenological implications of supersymmetry.

After providing some historical background, Weinberg introduces the reader to global and local supersymmetry and discusses in detail the supersymmetric version of the Standard Model, also addressing the question, where is supersymmetry broken? In the chapter "Beyond perturbation theory," general aspects of supersymmetry breaking are discussed, and the Seiberg-Witten solution of the supersymmetric Lagrangian with two supersymmetries is presented in a pedagogical manner. The book closes with an extensive introduction to supergravity and supersymmetry algebras in higher dimensions. All chapters close with an excellent selection of problems and a comprehensive reference list. The book surely will be an invaluable reference work for all physicists and for mathematicians working with supersymmetric theories, and it may also serve as a textbook for graduate courses.

In Supersymmetry: Unveiling the Ultimate Laws of Nature, Gordon Kane gives a nontechnical explanation of supersymmetry, with the goal of introducing a wider audience to the subject, which is also the aim of the foreword by Edward Witten. The first chapter motivates by asking: Where do we come from? What are we? and Where are we going? Then the Standard Model is introduced and Kane discusses in detail the predictions and the experimental foundations of the Standard Model. The fourth chapter explains what supersymmetry is and which problems it should solve. After introducing the reader to the conceptual framework of supersymmetry and explaining nicely how different levels of understanding of nature are described by effective theories, Kane takes the reader inside the giant particle accelerators, where the discovery of supersymmetry should occur. The role of supersymmetry in recent attempts to unify all forces of nature in a primary theory (string theory, M-theory) is discussed in the last chapters.—Bjorn Andreas, Physics, University of North Carolina at Chapel Hill