Combinatorics and Geometry of the AmplituhedronConfirmed

by Melissa Sherman-Bennett (University of California, Davis)

Friday Apr 24, 2026, 2:30 PM → 4:00 PM America/Toronto

PI/3-394 - Skyroom (Perimeter Institute for Theoretical Physics)

The amplituhedron was introduced by Arkani-Hamed and Trnka as a geometric object which "encodes" scattering amplitudes in N=4 SYM theory. One of their motivations was the Britto-Cachazo-Feng-Witten (BCFW) recursion for amplitudes, which in particular produced many different formulas for the same amplitude. Their expectation was that the amplitude is the "volume" of the amplituhedron, and the different BCFW formulas correspond to different ways of decomposing the amplituhedron into small pieces. This expectation is in fact correct. I'll discuss some of the mathematics going into the proof, some unexpected phenomena arising along the way, and some lingering questions. This is joint work with (various subsets of) Chaim Even-Zohar, Tsviqa Lakrec, Matteo Parisi, Ran Tessler, and Lauren Williams.