Weinberg's Compositeness

Abstract

Nearly 60 years ago Weinberg suggested a criterion for particle "compositeness", which has acquired new life with the discovery of new, exotic hadrons. His idea resonates with model-based intuition. I discuss the role it plays in the context of another of Weinberg's creations, the model-independent framework of effective field theories.Dedicated to the memory of Steven Weinberg, who always chose the right degrees of freedom.