The Operator Formalism

Abstract

In the previous chapter, the consequences of conformal symmetry on two-dimensional field theories were embodied in constraints imposed on correlation functions known as the Ward identities. These Ward identities were most easily expressed in the form of an operator product expansion of the energy-momentum tensor with local fields. It was implicit, however, that operator product expansions were occurring within correlation functions and no use was made of any operator formalism or Hilbert space: The correlation functions could in principle be obtained in the path integral formalism.