The combinatorial geometry of particle physics

Abstract: Recent breakthroughs in the study of scattering amplitudes have uncovered profound and unexpected connections with combinatorial geometry. These connections range from classical structures -- such as polytopes, matroids, and Grassmannians -- to more modern developments including positroid varieties and the amplituhedron. Together they point toward the unifying framework of positive geometry, in which geometric domains canonically determine analytic functions governing scattering processes. This survey traces the emergence of positive geometry from the physics of amplitudes, building towards recent progress on amplitudes for matroids.