Records from the S-Matrix Marathon: Selected Topics on Scattering Amplitudes

This book is a collection of pedagogical lecture notes on topics related to S-matrix theory. It presents recent progress in understanding the foundations of S-matrix theory from different perspectives, covering aspects such as analytic properties and infrared divergences, observables on time-folded contours and cosmological backgrounds, as well as lattice simulations and phenomenological applications in strongly-coupled QCD.

The chapters are based on lectures given at the S-Matrix Marathon workshop, hosted in Princeton during the spring of 2024. The purpose is to provide a pedagogical introduction to the evolving ideas surrounding S-matrix theory and to highlight emerging directions in the field. This book is intended for junior researchers and advanced students who are interested in deepening their understanding of particle interactions.

Nima Arkani-Hamed is a theorist with wide-ranging interests in fundamental physics, working at the Institute for Advanced Study in Princeton, NJ. He is concerned with the relationship between theory and experiment, with a special focus on current and future particle accelerators as well as cosmological observations.

Mathieu Giroux is a Ph.D. student at McGill University in Montréal, Canada. He earned a bachelor's degree in mathematics and physics, as well as a master's degree in physics from the same institution. He is interested in the formal aspects of quantum field theories, aiming to streamline computational methods.

Holmfridur Sigridar Hannesdottir is a member of the School of Natural Sciences at the Institute for Advanced Study in Princeton, NJ. She received a Ph.D. in physics from Harvard University, after completing a B.Sc. in physics from the University of Iceland. Her work focuses on theoretical aspects of quantum field theories, including the study of infrared divergences in gauge theories and constraining the analytic structure of Feynman integrals.

Sebastian Mizera is a postdoctoral researcher at Princeton University and a visiting scholar at the Institute for Advanced Study in Princeton, NJ. His work focuses on the foundations of scattering amplitudes.

Celina Pasiecznik is a Ph.D. student at McGill University in Montréal, Canada. She earned her bachelor's degree in physics from the University of Toronto, followed by master's degrees in mathematical physics from the University of Oxford and in aeronautics and astronautics from MIT. Celina's research now focuses on high-energy particle physics, particularly on scattering amplitudes involving gravitons.