We present a method, which constructs a suitable deformation vector in loop momentum space, when the loop integration is done numerically with the help of the subtraction method. The method presented here extends previously discussed techniques from the massless case to the general case of arbitrary masses in the loop.
@article{arxiv.1208.4088,
title = {Direct contour deformation with arbitrary masses in the loop},
author = {Sebastian Becker and Stefan Weinzierl},
journal= {arXiv preprint arXiv:1208.4088},
year = {2013}
}