Superconformal Invariance in Two Dimensions and the Tricritical Ising Model

We discuss the realization of superconformal invariance in two dimensional quantum field theory. The Hilbert space of a superconformal theory splits into two sectors; one a representation of the Neveu-Schwarz algebra, the other of the Ramond algebra. We introduce the spin fields which intertwine the two sectors and correspond to the irreducible representations of the Ramond algebra. We give the determinant formula for the Ramond algebra and the discrete list of possible unitary representations. We have previously noted that the Z 2 even sector of the tricritical Ising model is a representation of the NeveuSchwarz algebra. Here we complete the picture by showing that the Z 2 odd sector forms a representation of the Ramond algebra. This system is the first experimentally realizable supersymmetric field theory.