We relate a l-loop Feynman integral to a sum of phase space integrals, where the integrands are determined by the spanning trees of the original l-loop graph. Causality requires that the propagators of the trees have a modified iδ-prescription and we present a simple formula for the correct iδ-prescription.
@article{arxiv.1902.02135,
title = {Causality and loop-tree duality at higher loops},
author = {Robert Runkel and Zoltán Szőr and Juan Pablo Vesga and Stefan Weinzierl},
journal= {arXiv preprint arXiv:1902.02135},
year = {2019}
}
Comments
6 pages, v2: version to be published, v3: Theorem 1 corrected