This text offers a brief introduction to the dispersion relations as an approach to calculate S-matrix elements, a formalism that allows one to take advantage of the analytical structure of scattering amplitudes following the basic principles of unitarity and causality. First, the case of two-body scattering is considered and then its contribution to other processes through final-state interactions is discussed. For two-body scattering amplitudes, the general expression for a partial-wave amplitude is derived in the approximation where the crossed channel dynamics is neglected. This is taken as the starting point for many interesting nonperturbative applications, both in the light and heavy quark sector. Subsequently crossed channel dynamics is introduced within the equations for calculating the partial-wave amplitudes. Some applications based on methods that treat crossed-channel dynamics perturbatively are discussed too. The last part of this introductory treatment is dedicated to the further impact of scattering amplitudes on a variety of processes through final-state interactions. Several possible approaches are discussed such as the Muskhelishvili-Omnes dispersive integral equations and other closed formulae. These different formalisms are then applied in particular to the study of resonances presenting a number of challenging properties. The book ends with a chapter illustrating the use of dispersion relations in the nuclear medium for the evaluation of the energy density in nuclear matter.

Causality and Dispersion Relations

The necessity of describing three-nucleon and three-quark systems have led to a constant interest in the problem of three particles. The question of including relativistic effects appeared together with the consideration of the decay amplitude in the framework of the dispersion technique. The relativistic dispersion description of amplitudes always takes into account processes connected with the investigated reaction by the unitarity condition or by virtual transitions; in the case of three-particle processes they are, as a rule, those where other many-particle states and resonances are produced. The description of these interconnected reactions and ways of handling them is the main subject of the book.

The electromagnetic theory of Maxwell and the electron theory of Lorentz and Drude stimulated a great deal of experimental work on the optical properties of solids in the late nineteenth and early twentieth centuries. The time was not then ripe, however, for general progress in this field. The experimental techniques were not available to produce suitable specimens for optical measurements with well defined structure and purity. On the theoretical side, the classical electron theory provided only a very incomplete account of the interaction of light waves with matter. The centre of interest in optical research moved to atomic and molecular spectroscopy where quantitative results were easier to obtain. The quantum theory, starting with Bohr's theory of 1913, provided a highly successful basis for the interpretation of the optical spectra of atoms and molecules. The present-day theory of the optical properties of solids is based on the quantum theory of electrons in solids, developed from the early researches of Sommerfeld and Bloch, and the theory of lattice vibrations originating in the research by Born. The formal con nection between optical absorption and electron wave functions in solids has been well known since the 1930s but it is only recently that electron energy band calculations have achieved sufficient accuracy to make profitable a comparison of experimental and theoretical results. Without some guidance from a theoretical band structure calculation, it would be difficult to make any progress with the in terpretation of an optical absorption spectrum.

How do specific activities and institutions in which people are involved fit into the overall adaptive strategy of their society? What are the particular pressures leading to change in each of these spheres when the group's strategy of adaptation changes? What are the human demands made by a hunting-gathering strategy that lead to the development of particular family systems, modes of social control, religious beliefs and practices, values and ideologies, and personality structures? What are the new human demands that lead to the reorganization of these aspects of life as the group moves from one level of development to another? Man in Adaptation: The Institutional Framework introduces the institutional, psychological, and ideological dimensions of the strategies of adaptation that have characterized human societies from the earliest known forms of social life to the present. Cohen includes topics that are of principal anthropological concern—notably marriage, law and social control, religion and magic, value systems, personality, and art. There are no studies that deal with cultural change as such in this book. Where possible, Cohen includes articles that deal with changes in particular spheres of activity, such as family organization, law, religion, and value systems. He argues that change is not a special situation. Instead, culture is change and change is culture, and it is unrealistic to study change outside the specific social and technological organization of a given society. This volume unifies the subject matter of anthropology within a single and powerful explanatory framework and incorporates the work of the most renowned anthropological experts on man.

This collection brings together the principal sources in the development of the techniques of social network analysis, from early metaphorical statements in Simmel and Radcliffe-Brown through the more systematic explorations in sociology and social anthropology, to contemporary formalizations. A new introduction explores the history of Social Networks and highlights the arguments of those who treat social network analysis as a loose, qualitative approach as well as those who see its potential in technical, mathematical uses. The thematically organized coverage includes: * Part I: Conceptualizing Social Networks * Part II: Topics and Developments in Graph Theory * Part III: Further Mathematical Models for Networks * Part IV: Applications: Family and Community * Part V: Applications: Corporate Power and Economic Structures * Part VI: Applications: Political, Protest, and Policy Networks * Part VII: Applications: Knowledge, Reputation, and Diffusion

This book proposes a new interpretation of Claude Lefort’s thought focusing on his phenomenological method. Although all scholars recognize the influence of Merleau-Ponty, so far no one has demonstrated the fundamental coherence between Merleau-Ponty’s theory and the main concepts proposed by Lefort; in particular between the concept of institution and the definitions of social and democracy. If Merleau-Ponty uses the idea of institution to think beyond the division between subject and object, to think together continuity and difference, permanence and change, this same concept allows Lefort to understand society as both conflict and unity. From this starting point, this study will attempt to clarify Lefort’s concept of the political and his interpretations of modernity, humanism, and the work of Niccolò Machiavelli. These very concepts will show the difference from structuralism, Michel Foucault’s contemporary theory and theories of immanence. At the same time this study highlights an internal tension in Lefort’s own thinking: between autonomy and experience, institution and insurgence.