On the evaluation of sunset-type Feynman diagrams

We introduce an efficient configuration space technique which allows one to compute a class of Feynman diagrams which generalize the scalar sunset topology to any number of massive internal lines. General tensor vertex structures and modifications of the propagators due to particle emission with vanishing momenta can be included with only a little change of the basic technique described for the scalar case. We discuss applications to the computation of n -body phase space in D -dimensional spacetime. Substantial simplifications occur for odd space-time dimensions where the final results can be expressed in closed form through elementary functions. We present explicit analytical formulas for three-dimensional space-time.