Three-point density correlation functions in the fractional quantum Hall regime

In this paper we consider the three-particle density correlation function f or a fractional quantum Hall liquid. The study of this object is motivated by recent experimental studies of fractional quantum Hall systems using ine lastic light scattering and phonon absorption techniques. Symmetry properti es of the correlation function are noted. An exact sum rule is derived whic h this quantity must obey. This sum rule is used to assess the convolution approximation that has been used to estimate the matrix elements for such e xperiments.