Evaluating multi-loop Feynman diagrams with infrared and threshold singularities numerically

Abstract

We present a method to evaluate numerically Feynman diagrams directly from their Feynman parameters representation. We first disentangle overlapping singularities using sector decomposition. Threshold singularities are treated with an appropriate contour deformation. We have validated our technique comparing with recent analytic results for the gg->h two-loop amplitudes with heavy quarks and scalar quarks.

Comments: 8 pages, 3 figures; references added, version to appear in JHEP