Constructing Scattering Amplitudes [Tata-Infosys Lectures Series] (Lecture 2)

One of the main observables in particle physics is scattering amplitudes. The traditional approach to calculating scattering amplitudes involves summing over a combinatorially large number of Feynman diagrams of increasing complexity. Despite this, the final answer is often relatively simple in theories with symmetry. In this lecture series, we discuss how symmetries like electromagnetic duality, non-linearly realized symmetries, color-kinematic duality and positive geometry affect amplitudes. We introduce modern symmetry-driven techniques like recursion relations, generalized unitarity, Grassmannian geometry and the double copy to study scattering in a variety of special theories like Born-Infeld, Yang-Mills and chiral perturbation theories.