Dynamical four-spin two-time correlation functions in a high-temperature Heisenberg paramagnet

Abstract

We develop a general formalism for calculating four-spin two-time dynamical correlation functions in high-temperature paramagnets. The method used is similar to lowest-order diagrammatic approximations which have been successful in obtaining two-spin two-time dynamical correlation functions. In particular, the formalism is used on the Heisenberg paramagnet to obtain the energy-energy correlation function and related correlation functions measurable in Raman scattering or acoustic experiments.