General formula for symmetry factors of Feynman diagrams
Abstract
General formula for symmetry factors (S-factor) of Feynman diagrams containing fields with high spins is derived. We prove that symmetry factors of Feynman diagrams of well-known theories do not depend on spins of fields. In contributions to S-factors, self-conjugate fields and non self-conjugate fields play the same roles as real scalar fields and complex scalar fields, respectively. Thus, the formula of S-factors for scalar theories --- theories include only real and complex scalar fields --- works on all well-known theories of fields with high spins.Two interesting consequences deduced from our result are : (i) S-factors of all external connected diagrams consisting of only vertices with three different fields, e.g., spinor QED, are equal to unity; (ii) some diagrams with different topologies can contribute the same factor, leading to the result that the inverse S-factor for the total contribution is the sum of inverse S-factors, i.e., 1/S = \sum_i (1/S_i).
Keywords
Cite
@article{arxiv.1011.4142,
title = {General formula for symmetry factors of Feynman diagrams},
author = {L. T. Hue and H. T. Hung and H. N. Long},
journal= {arXiv preprint arXiv:1011.4142},
year = {2013}
}
Comments
22 pages, wick.sty needed, revised version, reference added, accepted in Reports on Mathematical Physics