3RD INTERNATIONAL WORKSHOP ON
THE INTERCONNECTION BETWEEN
PARTICLE PHYSICS AND COSMOLOGY

Professor Michael Dine works on problems in theoretical elementary particle physics and cosmology. He was among the first to suggest that supersymmetry, a hypothetical new symmetry of the laws of nature, might solve some of the outstanding problems of the "Standard Model" of elementary particles. This symmetry relates fermions (particles with fractional spin, such as the electron, proton and neutron) to bosons (particles with integer spin, like the photon, gluons, W^± and Z⁰) and implies the existence of many new particles. Since no such symmetry is observed at low energies, this symmetry must be "spontaneously broken"; Dine and collaborators were the first to show that in some supersymmetric theories, the dynamics of the theory lead to symmetry breakdown. With collaborators and students, he has developed the first successful supersymmetric extensions of the standard model in which supersymmetry is broken by low energy dynamics. These models make dramatic predictions for forthcoming experiments, and now provide one of the principal frameworks for supersymmetry phenomenology. Dine was also among those who proposed the "invisible axion" as a solution of the strong CP problem, and recognized its possible role as a candidate for the dark matter.

Superstring theories are candidate unified theories of all interactions, including Einstein's theory of gravitation. These theories are still not well understood, and it has proven difficult to extract experimental predictions from these theories. Dine's research into string theories has been aimed at developing a more complete understanding of these theories. In addition to contributing to the technical development of the subject, Dine has pointed out some of the obstacles to developing a phenomenology, and possible solutions.

Dine has also worked extensively on problems in cosmology. This work has included possible origins for the asymmetry between matter and antimatter. As pointed out long ago by Andrei Sakharov, within the framework of the big bang theory one can understand why the universe contains mostly matter, rather than equal amounts of matter and antimatter, provided that certain conditions are satisfied. Dine's efforts in this area have focused on two mechanisms, one exploiting baryon number violation in the standard model, the other (widely known as the "Affleck-Dine mechanism") involving coherent production of baryon number. Dine's work has also included enumeration of possible dark matter candidates, studies of cosmology and string theory, and issues in inflationary cosmology.