Grand Unified Theories

These course-tested lectures provide a technical introduction to Supersymmetric Grand Unified Theories (SUSY GUTs), as well as a personal view on the topic by one of the pioneers in the field. While the Standard Model of Particle Physics is incredibly successful in describing the known universe it is, nevertheless, an incomplete theory with many free parameters and open issues. An elegant solution to all of these quandaries is the proposed theory of SUSY GUTs. In a GUT, quarks and leptons are related in a simple way by the unifying symmetry and their electric charges are quantized, further the relative strength of the strong, weak and electromagnetic forces are predicted. SUSY GUTs additionally provide a framework for understanding particle masses and offer candidates for dark matter. Finally, with the extension of SUSY GUTs to string theory, a quantum-mechanically consistent unification of the four known forces (including gravity) is obtained. The book is organized in three sections: the first section contains a brief introduction to the Standard Model, supersymmetry and the Minimal Supersymmetric Standard Model. Then SUSY GUTs in four space-time dimensions are introduced and reviewed. In addition, the cosmological issues concerning SUSY GUTs are discussed. Then the requirements for embedding a 4D SUSY GUT into higher-dimensional theories including gravity (i.e. String Theory) are investigated. Accordingly, section two of the course is devoted to discussing the so-called Orbifold GUTs and how in turn they solve some of the technical problems of 4D SUSY GUTs. Orbifold GUTs introduce a new set of open issues, which are then resolved in the third section in which it is shown how to embed Orbifold GUTs into the E(8) x E(8) Heterotic String in 10 space-time dimensions.

Grand Unified Theories introduces the application of gauge field theories to a unified description of the strong, electromagnetic, weak, and gravitational interactions. The phenomenological aspects of the work are emphasized and explicit calculations presented. Many of the aspects of current research, including technicolor models, supersymmetry and supergravity, and the cosmological implications of these theories, are discussed in this book.This book is suitable for graduate students with a background in quantum mechanics, and experimental and theoretical particle physicists who want to understand the grand unified theories.

The theoretical understanding of elementary particle interactions has under gone a revolutionary change during the past one and a half decades. The spontaneously broken gauge theories, which in the 1970s emerged as a prime candidate for the description of electro-weak (as weIl as strong) interactions, have been confirmed by the discovery of neutral weak currents as weIl as the w- and Z-bosons. We now have a field theory of electro-weak interactions at energy scales below 100 GeV-the Glashow-Weinberg-Salam theory. It is a renormalizable theory which enables us to do calculations without en countering unnecessary divergences. The burning question now is: Wh at lies ahead at the next level of unification? As we head into the era of supercolliders and ultrahigh energy machines to answer this question, many ap, pealing possi bilities exist: left-right symmetry, technicolor, compositeness, grand unifica ti on, supersymmetry, supergravity, Kaluza-Klein models, and most recently superstrings that even unify gravity along with other interactions. Experi ments will decide if any one or any combination of these is to be relevant in the description of physics at the higher energies. As an outcome of our con fidence in the possible scenerios for elementary particle physics, we have seen our understanding of the early uni verse improve significantly.

Paul Adrian Maurice Dirac, one of the greatest physicists of the twentieth century, died in 1984. His college, St John's College, Cambridge, generously endowed annual lectures to be held at Cambridge University in his memory. This 1990 volume includes an expanded version of the third Dirac Memorial Lecture presented by Abdus Salam.

From Simon & Schuster, Superforce is Paul Davies' latest work that searches for a grand unified theory of nature. Superforce explains how recent discoveries in physics and the new cosmology have transformed concepts of the physical world by linking space, time, matter, force, creation, order, and mind into the ultimate scientific theory.

This book gives an answer, insofar as I knew it by early 2007, to a question: why hasn't the work of Randell Mills and his company, BlackLight Power, had a friendlier reception? Part of the answer: the 1989 cold fusion fiasco, with which Millsâ critics falsely identified him after he surfaced in The New York Times in 1991. Another part: Millsâ sweeping challenge to the theoretical physicists, whose pet theories astronomy has now shown can explain only 5% of everything out there, but who journal editors, scientists, graduate students, science writers, science managers, venture capitalists, the funding agencies, Congress, and the attentive public alike are still taught to hold in awe. The book is extensively documented for those who would like to read more about any of the topics mentioned. Its Table of Contents and Index are available as a free PDF download from the author's personal web page at http://homepage.mac.com/tstolper/