This book discusses group theory investigations of zincblende and wurtzite semiconductors under symmetry-breaking conditions. The text presents the group theory elements required to develop a multitude of symmetry-breaking problems, giving scientists a fast track to bypass the need for recalculating electronic states. The text is not only a valuable resource for speeding up calculations but also illustrates the construction of effective Hamiltonians for a chosen set of electronic states in crystalline semiconductors. Since Hamiltonians have to be invariant under the transformations of the point group, the crystal symmetry determines the multiplet structure of these states in the presence of spin-orbit, crystal-field, or exchange interactions. Symmetry-breaking leads to additional coupling of the states, resulting in shifts and/or splittings of the multiplets. Such interactions may be intrinsic, as in the case of the quasi-particle dispersion, or extrinsic, induced by magnetic, electric, or strain fields. Using a power expansion of the perturbations these interaction terms can be determined in their parameterized form in a unique way. The hierarchic structure of this invariant development allows to estimate the importance of particular symmetry-breaking effects in the Hamiltonian. A number of selected experimental curves are included to illustrate the symmetry-based discussions, which are especially important in optical spectroscopy. This text is written for graduate students and researchers who want to understand and simulate experimental findings reflecting the fine structure of electronic or excitonic states in crystalline semiconductors.

The conceptofspontaneous symmetry breaking plays a fundamental role in contemporary physics. It is essential for the description of degenerate ground states, massless modes, and topological defects. Examples are abundant in condensed matter physics, atomic and particle physics, as well as in astro physics and cosmology. In fact, spontaneous symmetry breaking can be re garded as a cornerstone ofa whole branch ofphysics which intersects the above mentioned traditionally distinct fields. In the year 2000 the European Science Foundation (ESF) started the Pro gramme "Cosmology in the Laboratory" (COSLAB), with the goal to search for and to develop analogies betweencondensed matterphysics, particle physics, and cosmology. Not surprisingly, spontaneous symmetry breaking is among the most useful notions in that endeavour. It has been decided that in the sec ond year of the Programme a School should be held in order to work out and deliver to a wide audience of students synthetic overviews of achievements and of current research topics of COSLAB. This idea has been supported by the Scientific and Environmental Affairs Division of NATO by including the School in the renowned series of its Advanced Study Institutes. The School, entitled" Patterns of Symmetry Breaking", was held in Cracow during 16-28 September 2002. It gathered 17 lecturers and about 60 students. The present volume contains notes ofmost of the lectures from that School. We hope that of the physics of spon it will convey to the reader the breadth and the beauty taneous symmetry breaking.

The new edition of this well received primer on rigorous aspects of symmetry breaking presents a more detailed and thorough discussion of the mechanism of symmetry breaking in classical field theory in relation with the Noether theorem. Moreover, the link between symmetry breaking without massless Goldstone bosons in Coulomb systems and in gauge theories is made more explicit. A subject index has been added and a number of misprints have been corrected.

The new edition of this well received primer on rigorous aspects of symmetry breaking presents a more detailed and thorough discussion of the mechanism of symmetry breaking in classical field theory in relation with the Noether theorem. Moreover, the link between symmetry breaking without massless Goldstone bosons in Coulomb systems and in gauge theories is made more explicit. A subject index has been added and a number of misprints have been corrected.

This volume collects a a number of contributions on spontaneous symmetry breaking. Current studies in this general field are going ahead at a full speed. The book present review chapters which give an overview on the major break throughs of recent years. It covers a number of different physical settings which are introduced when a nonlinearity is added to the underlying symmetric problems and its strength exceeds a certain critical value. The corresponding loss of symmetry, called spontaneous symmetry breaking, alias self-trapping into asymmetric states is extensively discussed in this book. The book presents both active theoretical studies of spontaneous symmetry breaking effects as well as experimental findings, chiefly for Bose-Einstein-Condensates with the self-repulsive nonlinearity, and also for photorefractive media in optics.

This book is an introduction to the concept of symmetries in electromagnetism and explicit symmetry breaking. It begins with a brief background on the origin of the concept of symmetry and its meaning in fields such as architecture, mathematics and physics. Despite the extensive developments of symmetry in these fields, it has yet to be applied to the context of classical electromagnetism and related engineering applications. This book unravels the beauty and excitement of this area to scientists and engineers.

These notes essentially reproduce lectures given at the International School for Advances Studies (Trieste) and at the Scuola Normale Superiore (Pisa) on various occasions. The scope of the short series of lectures was to extend on general grounds, also to mathematicians, the phenomenon of Spontaneous Symmetry Breaking (SSB), a mechanism which seems at the basis of the recent developments in theoretical physics (from statistical mechanics to many-body theory and to elementary particle theory). Besides its extraordinary success, the idea of SSB deserves being discussed also because of its innovative philosophical content and in our opinion it should be part of the background knowledge for mathematical and theoretical physics students, especially those who are interested in questions of principle and in general mathematical structures.