%0 Journal Article
%T Multiparticle tree amplitudes in scalar field theory
%A Fernando T Brandt
%A Josif Frenkel
%J Physics
%D 1995
%I arXiv
%R 10.1103/PhysRevD.53.2256
%X Following an argument advanced by Feynman, we consider a method for obtaining the effective action which generates the sum of tree diagrams with external physical particles. This technique is applied, in the unbroken \lambda \phi^4 theory, to the derivation of the threshold amplitude for the production of $n$ scalar particles by $n$ initial particles. The leading contributions to the tree amplitude, which become singular in the threshold limit, exhibit a factorial growth with n.
%U http://arxiv.org/abs/hep-th/9508048v1