Theoretical Elementary Particle Physics Research

This field studies the interplay between physical theories, the insights and intuitions obtained from them, and rigorous mathematics. This applies to many parts of physics, such as classical dynamical systems, statistical mechanics, condensed matter theory, astrophysics, elementary particle theory, gravitation, and string theory. For much of the last 20 years, the work of string theorists has stimulated important developments in geometry. Seiberg-Witten theory is one prime example, which has led to work in pure mathematics.

Quantum field theory is the major framework for the study of the interactions of elementary particles. Professor Freedman proposes to utilize new techniques for the computation of scattering amplitudes between these particles -- techniques which have supplanted the traditional approach via Feynman diagrams. He plans to focus on the properties of superamplitudes, which compactly package information concerning many different particle processes in a single expression. The initial goal, which has already met with success, is to use superamplitudes to explore properties of the N=8 supergravity theory. These properties are relevant to the conjecture that N=8 supergravity is the first consistent field theory of gravity at the quantum level. Numerous other applications of and extensions to this technology are envisioned.

There are several broader impacts associated with this work. At a scientific level, any increase in our ability to evaluate on-shell amplitudes is extremely valuable, for such amplitudes have been applied to subjects as diverse as the computation of background QCD events for the Large Hadron Collider at CERN and the search for an ultraviolet-finite field theory of quantum gravity. Furthermore, this subject matter is an excellent area for the advanced education and training of young researchers.