3:30–4:30 pm Maria Goeppert-Mayer Lecture Hall
The DNA of Particle Scattering
Lance Dixon, Stanford University
Scattering amplitudes are the main arena where quantum field theory meets particle experiments, especially at the Large Hadron Collider where the copious scattering of quarks and gluons in quantum chromodynamics (QCD) produces Higgs bosons and many backgrounds to searches for new physics. For decades, it has been realized that the scattering of particles in gauge theories like QCD is far simpler than standard perturbative approaches would suggest. New approaches based on unitarity and bootstrapping have massively simplified many computations previously done with Feynman diagrams. Still, the final results are often highly intricate, multivariate mathematical functions, which are difficult to describe, let alone compute. In many cases, the functions have a "genetic code" underlying them, called the symbol, which reveals much of their structure. The symbol of such a function is a linear combination of words, sequences of letters analogous to sequences of DNA base pairs. Understanding the alphabet, and then reading the code, exposes the physics and mathematics underlying the scattering process. Remarkably, the two scattering amplitudes known to the highest orders in perturbation theory (7 and 8 loops) are related to each other by a mysterious duality, which involves reading the code backwards as well as forwards.