In this paper, we consider the two-loop sunset diagram with two different masses, m and M, at spacelike virtuality q^2 = -m^2. We find explicit representations for the master integrals and an analytic result through O(epsilon) in d=4-2epsilon space-time dimensions for the case of equal masses, m = M.
@article{arxiv.hep-ph/0510235,
title = {Two-loop sunset diagrams with three massive lines},
author = {B. A. Kniehl and A. V. Kotikov and A. Onishchenko and O. Veretin},
journal= {arXiv preprint arXiv:hep-ph/0510235},
year = {2010}
}