Ben Heidenreich (UMass Physics): What is Quantum Field Theory

I discuss the main ingredients of a (covariant, UV-complete) quantum field theory in modern language, providing both the canonical and path-integral perspectives. I will illustrate this discussion with some elementary examples such as the compact free boson and Maxwell theory. I will also discuss how physicists work with more complicated theories (such as Yang-Mills theory) even when their construction is not fully understood.