Eur. Phys. J. C (2002) 23: 701-706
https://doi.org/10.1007/s100520200889

Theoretical physics

Counting tree diagrams: asymptotic results for QCD-like theories

University of Nijmegen, 6500 GI, Nijmegen, The Netherlands

^* e-mail: petros@sci.kun.nl

Received: 17 October 2001
Published online: 5 April 2002

Abstract

We discuss the enumeration of Feynman diagrams at tree order for processes with external lines of different types. We show how this can be done by iterating algebraic Schwinger–Dyson equations. Asymptotic estimates for very many external lines are derived. Applications include QED, QCD and scalar QED, and the asymptotic estimates are numerically confronted with the exact results.