THE SUNSET DIAGRAM IN SU(3) CHIRAL PERTURBATION-THEORY

A general procedure for the calculation of a class of two-loop Feynman diagrams is described. These are two-point functions containing three massive propagators, raised to integer powers, in the denominator and arbitrary polynomials of the loop momenta in the numerator. The ultra violet divergent parts are calculated analytically, while the remainin g finite parts are obtained by one-dimensional numerical integration, both below and above the threshold. Integrals of this type occur, for example, in chiral perturbation theory at order p(6).