English

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.

Keywords

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