Continuum derivation of the Ising model two-point function

Abstract

A new derivation is presented of the exact result of Wu, McCoy, Tracy, and Barouch for the scaling-limit spin-spin correlation function in the two-dimensional Ising model. The starting point is a Fredholm determinant representation which may be obtained either in the Pfaffian formalism, or in the algebraic approach using field theory methods. The connection of this work with the quantum sine-Gordon theory is discussed.