Flow Oriented Perturbation Theory (FOPT) is a novel approach to Feynman diagrams based on the coordinate (position) space description of Quantum Field Theories (QFT). It is a coordinate space analogue of time-ordered perturbation theory and loop-tree duality. Within this approach, a generic Feynman graph is mapped to a sum of all its possible different energy-flows respecting energy conservation at each vertex.
FOPT offers interesting features regarding the computation of higher-loop Feynman amplitudes such as combinatorial and canonical Feynman rules, explicit infrared singularity factorization on a per-diagram level and the potential to have manifest cancellation of real and virtual singularities.
I will conclude by discussing the extension of FOPT to massless fermion fields and indicate steps towards the treatment of massive lines in arbitrary dimensions.
Based on https://arxiv.org/abs/2210.05532
IFIC seminar organizers