Space-Time, Quantum Mechanics and Scattering Amplitudes

by Nima Arkani-Hamed (IAS Princeton)

Thursday 4 Nov 2010, 14:30 → 15:30 Europe/Zurich

Auditoire 1 du BSP Cubotron (EPFL)

Scattering amplitudes in gauge theories and gravity have extraordinary properties that are completely invisible in the textbook formulation of quantum field theory.
The standard way of computing these amplitudes, using Feynman diagrams, make space-time locality and quantum-mechanical unitarity manifest. However In the last twenty years, it has become clear that apart from the very simplest processes, Feynman diagrams are exceedingly complicated, and furthermore completely hide remarkable features of the final result. This strongly suggests that there is a new way of thinking about quantum field theory where the unitary description of a scattering process in space-time will not play a central role, but other hidden physical principles will be made more manifest. The past few years have seen very rapid developments towards uncovering this new picture, especially for the maximally supersymmetric gauge theory in four dimensions, combining a remarkable collection of ideas from string theory, integrable systems, twistor theory as well as new mathematical structures in algebraic
geometry and the theory of motives. In this talk I will review these ideas and discuss the various current directions of research.