Taking the Amplituhedron to the Limit

by Mr Joris Koefler (Max Planck Institute for Mathematics in the Sciences Leipzig)

Wednesday Nov 12, 2025, 3:00 PM → 4:00 PM Europe/Berlin

A.1.01/03 - Alps (MPP)

The amplituhedron is a semi-algebraic set given as the image of the positive Grassmannian under a linear map subject to a choice of additional parameters. We define the limit amplituhedron as the limit of amplituhedra by sending one of the parameters to infinity. We derive its algebraic boundary in terms of Chow varieties and explain its geometric interpretation from the point of view of Positive Geometry in terms of secants of the rational normal curve. This discussion shows that the limit amplituhedron is a positive geometry with a unique differential form.

Joint work with Rainer Sinn.