Today the workshop on Scattering Amplitudes and Cosmology starts. It takes place at the International Centre for Theoretical Physics (ICTP) in Trieste from April 17 to April 21. Nima Arkani-Hamed, Institute for Advanced Study (IAS), Princeton, USA, Johannes Henn, Max Planck Institute for Physics, Munich, Germany, and Jaroslav Trnka, University of California, Davis, USA, organize the event to bring together experts from scattering amplitudes, mathematics, and cosmology.
There are strong indications from physics at infinitesimal and cosmic distances that our current understanding of the laws of nature is only approximate. Novel geometric objects recently discovered in particle physics and cosmology have opened up entirely unexpected connections to combinatorics, algebra and geometry.
In the last decades researchers have uncovered tremendous insights into the structure of perturbative on-shell scattering amplitudes. This includes unitarity methods, recursion relations, worldsheet models, bootstrap methods and more recently an intriguing connection to positive geometry, which includes the positive Grassmannian, the Associahedron and the Amplituhedron. These advances bring us closer to reformulating the perturbative S-matrix via a completely new set of principles.
At the same time, positive geometry is also seen to be relevant to cosmological correlators, which are fundamental objects capturing the physics of our Universe. While some progress has been made bridging these two fields, we are still at the beginning of this road.