This book is devoted to one of the most relevant problems of modern cosmology: the formation of structures in the framework of big bang cosmology. The standard theory of gravitational instability has met with great success but has also encountered significant difficulties. In this book the alternative possibility offered by topological defects is explored in detail. A pedagogical introduction to the problem is given and several theoretical aspects of the problem are reviewed. Special emphasis is placed on the observable consequences of the presence of topological defects, and in particular their interaction with cosmic background radiation; other observable effects are also discussed. In addition, laboratory experiments on topological defects are dealt with. This book will, for a long time, serve as one of the best references, on the topic for students and researchers in cosmology.

Topological defects formed at symmetry-breaking phase transitions play an important role in many different fields of physics. They appear in many condensed-matter systems at low temperature; examples include vortices in superfluid helium-4, a rich variety of defects in helium-3, quantized mag netic flux tubes in type-II superconductors, and disclination lines and other defects in liquid crystals. In cosmology, unified gauge theories of particle interactions suggest a sequence of phase transitions in the very early uni verse some of which may lead to defect formation. In astrophysics, defects play an important role in the dynamics of neutron stars. In 1997 the European Science Foundation started the scientific network "Topological defects" headed by Tom Kibble. This network has provided us with a unique opportunity of establishing a collaboration between the representatives of these very different branches of modern physics. The NATO-ASI (Advanced Study Institute), held in Les Houches in February 1999 thanks to the support of the Scientific Division of NATO, the European Science Foundation and the CNRS, represents a key event of this ESF network. It brought together participants from widely different fields, with diverse expertise and vocabulary, fostering the exchange of ideas. The lectures given by particle physicists, cosmologists and condensed matter physicists are the result of the fruitful collaborations established since 1997 between groups in several European countries and in the U.S.A.

If one knows the exact properties of a vacuum, one can predict everything. This book reviews and discusses our present understanding of “nothing”. The main results from LEP, HERA and FERMILAB are presented. In addition, new projects are discussed, as well as the current status of Higgs phenomenology and the search for supersymmetry at the major laboratories.

Cosmology in Gauge Field Theory and String Theory focuses on the cosmological implications of the gauge theories of particle physics and of string theory. The book first examines the universe's series of phase transitions in which the successive gauge symmetries of the higher-temperature phase were spontaneously broken after the big bang, discussing relics of these phase transitions, more generic relics (baryons, neutrinos, axions), and supersymmetric particles (neutralinos and gravitinos). The author next studies supersymmetric theory, supergravity theory, and the constraints on the underlying field theory of the universe's inflationary era. The book concludes with a discussion of black hole solutions of the supergravity theory that approximates string theory at low energies and the insight that string theory affords into the microscopic origin of the Bekenstein-Hawking entropy. Cosmology in Gauge Field Theory and String Theory provides a modern introduction to these important problems from a particle physicist's perspective. It is intended as an introductory textbook for a first course on the subject at a graduate level.