Title: Modern Scattering Amplitude Methods for Particles and Strings

Speaker: Dr. Pinaki Banerjee, IAS, Princeton

Abstract: Scattering amplitudes are one of the most important observables in physics. In perturbative quantum field theoretic context the most famous and useful way of obtaining them is via Feynman diagrams. Although the Feynman diagrammatic technique is remarkably successful, it has several practical and conceptual limitations. With these shortcomings in mind, people have explored different alternative ways of obtaining scattering amplitudes. "Modern/ on-shell methods" is an umbrella term that encompasses all these approaches of computing scattering amplitudes without introducing any "off-shell" entities e.g. fields. In this talk, I shall focus on two such on-shell approaches that I have been working on, namely, (a.) obtaining scattering amplitudes for interacting scalars from Positive Geometries and (b.) some aspects of high energy string amplitudes from the worldsheet.