Near threshold expansion of Feynman diagrams
High Energy Physics - Phenomenology
2007-05-23 v1
Abstract
The near threshold expansion of Feynman diagrams is derived from their configuration space representation, by performing all x integrations. The general scalar Feynman diagram is considered, with an arbitrary number of external momenta, an arbitrary number of internal lines and an arbitrary number of loops, in n dimensions and all masses may be different. The expansions are considered both below and above threshold. Rules, giving real and imaginary part, are derived. Unitarity of a sunset diagram with I internal lines is checked in a direct way by showing that its imaginary part is equal to the phase space integral of I particles.
Cite
@article{arxiv.hep-ph/0508234,
title = {Near threshold expansion of Feynman diagrams},
author = {E. Mendels},
journal= {arXiv preprint arXiv:hep-ph/0508234},
year = {2007}
}
Comments
57 pages, 7 figures