A new technique for computing the spectral density of sunset-type diagrams: integral transformation in configuration space

We present a new method to investigate a class of diagrams which generalize s the sunset topology to any number of massive internal lines. Our attentio n is focused on the computation of the spectral density of these diagrams w hich is related to many-body phase space in D dimensional space-time. The s pectral density is determined by the inverse K-transform of the product of propagators in configuration space. The inverse K-transform reduces to the inverse Laplace transform in any odd number of space-time dimensions for wh ich we present an explicit analytical result. (C) 1998 Elsevier Science B.V . All rights reserved.