This award supports the research of Wafic Sabra, from the American University of Beirut (AUB).
After the success of the unification of the fundamental particle interactions within the standard model, the most pressing question in theoretical physics has since been the unification of the laws of quantum mechanics with the theory of general relativity, as well as the incorporation of quantum gravity with the other fundamental forces in a unified theory. Superstring theory is the leading candidate for a consistent finite theory unifying quantum gravity with the other forces of nature. The phenomenology derived from superstrings may have relevance to the problems encountered in the study of the black holes, particle physics and cosmology. In recent years, a new picture has emerged pointing to the existence of a fundamental theory, M-theory. Many theories behave very nicely if there is a small parameter, since one can perturbatively expand in this parameter and make sensible predictions. This new fundamental theory behaves like string theory at the perturbative level, but at the nonperturbative level, in which there are no small parameters, it has a rich structure of symmetries connecting perturbative aspects of string theory to nonperturbative states. This project will study gravitational backgrounds in these theories, focusing on black holes in higher numbers of dimensional backgrounds. The interdisciplinary nature of the proposed research will make it of benefit to both physicists and mathematicians working in fields related to string theory and differential geometry. It will also help in the development of the graduate programs in physics and mathematics at AUB, and in introducing students to the frontiers of research, particularly in the various fields of high energy physics.
M-theory behaves like string theory at the perturbative level, but at the nonperturbative level has a rich structure of duality symmetries connecting perturbative excitations to solitonic states. A major development is the equivalence between string theory on anti-de Sitter spaces and certain superconformal Yang-Mills gauge theories living on the boundary of these spaces. This equivalence gave more importance to the study of gravitational anti-de Sitter configurations as they provide a tool to the study of quantum gauge field theories important for particle physics. The main focus of Sabra's supported research is: a) The study and the classification of supersymmetric and non-supersymmetric gravitational backgrounds in various spacetime dimensions and in particular the search for black rings in gauged supergravity models. b)The study of gravitational instantons and their relation to integrable models, Einstein--Weyl structures and black holes in higher dimensions as well as the interpretation of Euclidean supergravity solutions in terms of string and M-theory. c) The development of our understanding of the nonperturbative theory underlying string theory, and incorporating this in the study of the phenomenological implications of string theory to gravitational physics, particle physics and cosmology
