Paper
An Algorithm to Compute Born Scattering Amplitudes without Feynman Graphs
Authors
F. Caravaglios, M. Moretti
Abstract
In this paper we suggest an {\it iterative} algorithm to compute automatically the scattering matrix elements of any given effective lagrangian, . By exploiting the relation between and the connected Green function generator, , we provide a formula which does not require the use of the Feynman graphs and it is suitable to implement a numerical routine. By means of this algorithm we have built a relatively simple and fast fortran code which we have used to calculate, at the tree level, the rate of four fermion production at LEP I\negthinspace{I} (finding a very good agreement with previous calculation) with and without the emission of one observable photon.