Aspects of Unitarity

Jan 15, 2019 - 1:30 pm to 2:30 pm

Campus, PAB 232

Jed Thompson

The term “unitarity” gets bandied about a lot in theoretical physics, but although it’s a very simple concept, its physical consequences are often less obvious.  In this talk, we’ll state concretely what we mean by unitarity, and work through how it implies the optical theorem.  We’ll then use the optical theorem to prove the narrowing of the diffraction peak at high energies and the Boltzmann H-theorem.  We will also give a heuristic derivation of the Froissart bound (which limits how quickly cross-sections can grow with energy), and if time permits give a rigorous proof.